In playing with my el-cheapo dyno program it looks like you can get the same HP with either a 71mm or 78mm stroke. The 78mm however gives a bit more torque.
Over all the CAM seems to give the biggest improvement.
The question is - is it worth the hassle to go to 78mm stroke (T1 rods, special pistons, clearence issues, cost of rods, crank, pistons) for 10'lb of torque??
Looks like 96mm x 71mm with good heads, proper CAM, optimun fuel delivery, FI or Carb, will make a pretty good motor.
Comments??
Ken
Full Version: 96x71 or 96x78 motor - That's the question
Torque is nice but the shorter stroke is going to rev higher. And the 96x71 should be more reliable.
It really depends on your end result.
What are you looking to do with this car when finished?
It's all in the package...!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Give us some more data to work with.
Twystd1
What are you looking to do with this car when finished?
It's all in the package...!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Give us some more data to work with.
Twystd1
I'm sorry but those desktop dyno programs are most of the time BS.
Just sticking a great big cam in an engine is about the biggest mistake an amateur engine builder makes.
There is no replacement for displacement.
and
Your engine is only as strong as its weakest link.
Just sticking a great big cam in an engine is about the biggest mistake an amateur engine builder makes.
There is no replacement for displacement.
and
Your engine is only as strong as its weakest link.
This is the set-up.
96mm pistons
44 webbers - 36mm venturie
4 to 1 headers, Phase 10 muffler
WEB CAM 86 - not firm on this yet
Heads upgaded to 44 x 38
So is it worth $1000 to go to a 78mm crank over the 71mm crank??
This comment below needs more to go with it to be of value.
"There is no replacement for displacement.
and
Your engine is only as strong as its weakest link."
Ken
96mm pistons
44 webbers - 36mm venturie
4 to 1 headers, Phase 10 muffler
WEB CAM 86 - not firm on this yet
Heads upgaded to 44 x 38
So is it worth $1000 to go to a 78mm crank over the 71mm crank??
This comment below needs more to go with it to be of value.
"There is no replacement for displacement.
and
Your engine is only as strong as its weakest link."
Ken
Raby has graphs posted for all his engines at www. aircooledtechnology.com. You can use them a base of comparison against each other. The difference between his 2056 Daily Driver + and his 2270 Peformer is pretty substantial. Hope the chart works:
Torque
rpm......2056.......2270
2000......104.........129......+25
4500......130.........162......+32
5500......119.........144......+25
6000......104.........135......+31
6500.......?............122......+
HP
rpm......2056.......2270
2000.......40..........61........+21
4500......112........139.......+27
5500......125........151......+26
6000......104........154......+50
6500.......?...........151......+
To me the 2270 is clearly in a different league than the 2056. I did take a ride in McMarks 2056 equiped car with a mild cam. He dynoed it at 90hp at the wheels which would be about 105hp at the crank. I can say that it made the car move nicely - much much faster than my stock 160k mile 2L engine. To me his engine made the 914 feel like the car it always should have been. Still, I can't stop thinking that a 2270 would make the 914 faster than my 911SC and be comparable to most six conversions.
Torque
rpm......2056.......2270
2000......104.........129......+25
4500......130.........162......+32
5500......119.........144......+25
6000......104.........135......+31
6500.......?............122......+
HP
rpm......2056.......2270
2000.......40..........61........+21
4500......112........139.......+27
5500......125........151......+26
6000......104........154......+50
6500.......?...........151......+
To me the 2270 is clearly in a different league than the 2056. I did take a ride in McMarks 2056 equiped car with a mild cam. He dynoed it at 90hp at the wheels which would be about 105hp at the crank. I can say that it made the car move nicely - much much faster than my stock 160k mile 2L engine. To me his engine made the 914 feel like the car it always should have been. Still, I can't stop thinking that a 2270 would make the 914 faster than my 911SC and be comparable to most six conversions.
"There is a replacement for displacement. It's called good engineering."
Displacement isn't everything, but you are rather limited on how much engineering you can do when you're using someone else's design. My quote isn't completely true either, but it's what I say to people who only think bigger is better. That's why Porsches modern 5.7 liter engine has almost twice the output of Chevy's modern 5.7 liter engines. 78mm WILL give you more torque, but unless you're going with longer cylinders and/or severely offset wrist pins, your rod angle is gonna go to hell. This will cost you in reliability to bottom end as well as the extra wear on your rings. It will also cost you the ability to rev, as I think someone mentioned, AND some tourqe perportionally to the length of your stroke.
As Twystd1 said, it all depends on what you're using it for. If you are concerned about cost (as many of us are), it sounds like you're not going to want the rebuild the thing very often. In that case, I would go with the 71mm stroke. However, if I was building a drag motor, especially if it were forced induction, then I would go with the extra torque and displacement at the expense of some reliability. MY OPINION.
Mark D.
Displacement isn't everything, but you are rather limited on how much engineering you can do when you're using someone else's design. My quote isn't completely true either, but it's what I say to people who only think bigger is better. That's why Porsches modern 5.7 liter engine has almost twice the output of Chevy's modern 5.7 liter engines. 78mm WILL give you more torque, but unless you're going with longer cylinders and/or severely offset wrist pins, your rod angle is gonna go to hell. This will cost you in reliability to bottom end as well as the extra wear on your rings. It will also cost you the ability to rev, as I think someone mentioned, AND some tourqe perportionally to the length of your stroke.
As Twystd1 said, it all depends on what you're using it for. If you are concerned about cost (as many of us are), it sounds like you're not going to want the rebuild the thing very often. In that case, I would go with the 71mm stroke. However, if I was building a drag motor, especially if it were forced induction, then I would go with the extra torque and displacement at the expense of some reliability. MY OPINION.
Mark D.
QUOTE(BMXerror @ Jun 13 2006, 05:23 PM) 
"There is a replacement for displacement. It's called good engineering."
Displacement isn't everything, but you are rather limited on how much engineering you can do when you're using someone else's design. My quote isn't completely true either, but it's what I say to people who only think bigger is better. That's why Porsches modern 5.7 liter engine has almost twice the output of Chevy's modern 5.7 liter engines. 78mm WILL give you more torque, but unless you're going with longer cylinders and/or severely offset wrist pins, your rod angle is gonna go to hell. This will cost you in reliability to bottom end as well as the extra wear on your rings. It will also cost you the ability to rev, as I think someone mentioned, AND some tourqe perportionally to the length of your stroke.
As Twystd1 said, it all depends on what you're using it for. If you are concerned about cost (as many of us are), it sounds like you're not going to want the rebuild the thing very often. In that case, I would go with the 71mm stroke. However, if I was building a drag motor, especially if it were forced induction, then I would go with the extra torque and displacement at the expense of some reliability. MY OPINION.
Mark D.
did you see the graphs above?
have you read any postings of Raby's about his motors or these combos??
I gather not...the Type IV really seems to wake up with the additional rod length without any real negative effects. As for the Porsche 5.7 putting out 2X that of the Chevy 5.7??? What are you smoking??
Cough, LS1, LS6...
end cough.
end cough.
[quote name='BMXerror' date='Jun 13 2006, 04:23 PM' post='702860']
"There is a replacement for displacement. It's called good engineering."
Displacement isn't everything, but you are rather limited on how much engineering you can do when you're using someone else's design. My quote isn't completely true either, but it's what I say to people who only think bigger is better. That's why Porsches modern 5.7 liter engine has almost twice the output of Chevy's modern 5.7 liter engines. 78mm WILL give you more torque, but unless you're going with longer cylinders and/or severely offset wrist pins, your rod angle is gonna go to hell. This will cost you in reliability to bottom end as well as the extra wear on your rings. It will also cost you the ability to rev, as I think someone mentioned, AND some tourqe perportionally to the length of your stroke.
As Twystd1 said, it all depends on what you're using it for. If you are concerned about cost (as many of us are), it sounds like you're not going to want the rebuild the thing very often. In that case, I would go with the 71mm stroke. However, if I was building a drag motor, especially if it were forced induction, then I would go with the extra torque and displacement at the expense of some reliability. MY OPINION.
Mark D.
[/quote
Please do yourself a favor and read a little on the topic before you waste all that time writing B.S.
Enjoy!
http://www.aircooledtechnology.com/vw_2270t4torquer.htm
"There is a replacement for displacement. It's called good engineering."
Displacement isn't everything, but you are rather limited on how much engineering you can do when you're using someone else's design. My quote isn't completely true either, but it's what I say to people who only think bigger is better. That's why Porsches modern 5.7 liter engine has almost twice the output of Chevy's modern 5.7 liter engines. 78mm WILL give you more torque, but unless you're going with longer cylinders and/or severely offset wrist pins, your rod angle is gonna go to hell. This will cost you in reliability to bottom end as well as the extra wear on your rings. It will also cost you the ability to rev, as I think someone mentioned, AND some tourqe perportionally to the length of your stroke.
As Twystd1 said, it all depends on what you're using it for. If you are concerned about cost (as many of us are), it sounds like you're not going to want the rebuild the thing very often. In that case, I would go with the 71mm stroke. However, if I was building a drag motor, especially if it were forced induction, then I would go with the extra torque and displacement at the expense of some reliability. MY OPINION.
Mark D.
[/quote
Please do yourself a favor and read a little on the topic before you waste all that time writing B.S.
Enjoy!
http://www.aircooledtechnology.com/vw_2270t4torquer.htm
Ken,
The motor I sold to Mark Henry was going to be a 94mm X 78mm engine. (still should be since I think Mark is putting it together with all the components I sold him)...Jake helped me with the selection of components, the idea was that with the stock 2.0 heads I had, the extra stroke and smaller bore would allow the cylinders more time to ingest the air/fuel mixture. With the cam spec'd by Jake, he thought 160hp was not out of the question...very similar to the 2270 posted above, but with the bone stock 2.0 heads, probebly lacking a little here and there....still would have been a fun motor...
The motor I sold to Mark Henry was going to be a 94mm X 78mm engine. (still should be since I think Mark is putting it together with all the components I sold him)...Jake helped me with the selection of components, the idea was that with the stock 2.0 heads I had, the extra stroke and smaller bore would allow the cylinders more time to ingest the air/fuel mixture. With the cam spec'd by Jake, he thought 160hp was not out of the question...very similar to the 2270 posted above, but with the bone stock 2.0 heads, probebly lacking a little here and there....still would have been a fun motor...
First - Let keep this discussion civilized, everybody is entitled to their comments. To many of these threads go off course do to non-technical comments.
Any way - my Dyno program my not give an accurate HP number, but it should be OK in showing changes up or down. For the same CFM, CAM, BORE, EXAHUST, C/R changing only the STROKE the HP stay about the same but with more TORQUE for the 78mm Crank over the 71mm.
Ken
Any way - my Dyno program my not give an accurate HP number, but it should be OK in showing changes up or down. For the same CFM, CAM, BORE, EXAHUST, C/R changing only the STROKE the HP stay about the same but with more TORQUE for the 78mm Crank over the 71mm.
Ken
QUOTE(KenH @ Jun 13 2006, 05:57 PM)
First - Let keep this discussion civilized, everybody is entitled to their comments. To many of these threads go off course do to non-technical comments.
Any way - my Dyno program my not give an accurate HP number, but it should be OK in showing changes up or down. For the same CFM, CAM, BORE, EXAHUST, C/R changing only the STROKE the HP stay about the same but with more TORQUE for the 78mm Crank over the 71mm.
Ken
Does the dyno program plot out the VE of the proposed combos?
Since when did Raby's articles become the VW bible? No offense to Jake, but he's still a human being. He has his opinions on the way things should be built and I have mine. And as with everything to do with technology, there's more than one way to solve a problem. So.Cal.914 asked our opinions. I gave my opinion. I even qualified it as ONLY my opinion. If you don't like my opinion, counter it with YOUR opinion instead of trying to discredit me with someone else's opinion.
And as for the Porsche/Chevy comparison, I'm talking about factory specs before OTHER people get ahold of the motors and mod them. Chevy Camero: 325 HP Porsche Carrera GT: 612 HP. ALMOST twice as much from the factory.
Mark D.
And as for the Porsche/Chevy comparison, I'm talking about factory specs before OTHER people get ahold of the motors and mod them. Chevy Camero: 325 HP Porsche Carrera GT: 612 HP. ALMOST twice as much from the factory.
Mark D.
QUOTE(Mueller @ Jun 13 2006, 08:46 PM)
Ken,
The motor I sold to Mark Henry was going to be a 94mm X 78mm engine. (still should be since I think Mark is putting it together with all the components I sold him)...Jake helped me with the selection of components, the idea was that with the stock 2.0 heads I had, the extra stroke and smaller bore would allow the cylinders more time to ingest the air/fuel mixture. With the cam spec'd by Jake, he thought 160hp was not out of the question...very similar to the 2270 posted above, but with the bone stock 2.0 heads, probebly lacking a little here and there....still would have been a fun motor...
Mike, you were going to build it with stock heads? Was this engine planned for turboing (hence extra air being forced in)?
[quote name='jd74914' date='Jun 13 2006, 06:05 PM' post='702898']
[quote name='Mueller' post='702881' date='Jun 13 2006, 08:46 PM']
Ken,
Mike, you were going to build it with stock heads? Was this engine planned for turboing (hence extra air being forced in)?
[/quote]
yep stock heads..that is why I went with the 94mm bore instead of the 96mm bore, the larger bore (and stroke) would benifit or would for sure need head work...this motor would have worked normally asperated or with the small turbo I have..that is how Jake and I had planned it from the start... (still going to install the turbo on my 1.8)...
Mark, I don't even know where to start....you cannot compare a pushrod V8 in a pedestrian grocery getter to a purpose built V10 barely streetable racecar...as for quoting Jake, I've done quite a bit of homework on the Type IV's and learned from Jake and others (still learning)
[quote name='Mueller' post='702881' date='Jun 13 2006, 08:46 PM']
Ken,
Mike, you were going to build it with stock heads? Was this engine planned for turboing (hence extra air being forced in)?
[/quote]
yep stock heads..that is why I went with the 94mm bore instead of the 96mm bore, the larger bore (and stroke) would benifit or would for sure need head work...this motor would have worked normally asperated or with the small turbo I have..that is how Jake and I had planned it from the start... (still going to install the turbo on my 1.8)...
Mark, I don't even know where to start....you cannot compare a pushrod V8 in a pedestrian grocery getter to a purpose built V10 barely streetable racecar...as for quoting Jake, I've done quite a bit of homework on the Type IV's and learned from Jake and others (still learning)
OK, but here's the rub.
Just because the stock stroke is shorter it doesn't equal less wear or higher rev's. Stock rods are about 815g and the aftermarket type 1 rods are 590g, so that alone is close to a half pound less being tossed around. If you're using stock pistons they weigh 710g, my 102mm JE's weigh in at 510g (so I expect the 96mm KB, 22mm pin are the same or less) so if your using a stock piston (or KB with a 24mm pin) you're now pushing almost an extra pound per journal. Multiply that pound by 6000rpm
Unless you are using $1200.+ Carrillo rods and $1000. JE 22mm pin pistons you just lost any advantage you may have had from the shorter stroke.
At any rate even if you stick with stock rods you should upgrade to ARP rod bolts so there's $150
Also note in those dyno graphs that both torque and HP are done at 5800rpm, so being able the rev higher doesn't mean a whole lot.
If the 78mm crank is counterweighted, with a proper balance it has less harmonics, add lighter rods and pistons equals less wear at high HP levels. The rod angle ratio with a 5.400 rod is not that extreme.
Just because the stock stroke is shorter it doesn't equal less wear or higher rev's. Stock rods are about 815g and the aftermarket type 1 rods are 590g, so that alone is close to a half pound less being tossed around. If you're using stock pistons they weigh 710g, my 102mm JE's weigh in at 510g (so I expect the 96mm KB, 22mm pin are the same or less) so if your using a stock piston (or KB with a 24mm pin) you're now pushing almost an extra pound per journal. Multiply that pound by 6000rpm
Unless you are using $1200.+ Carrillo rods and $1000. JE 22mm pin pistons you just lost any advantage you may have had from the shorter stroke.
At any rate even if you stick with stock rods you should upgrade to ARP rod bolts so there's $150
Also note in those dyno graphs that both torque and HP are done at 5800rpm, so being able the rev higher doesn't mean a whole lot.
If the 78mm crank is counterweighted, with a proper balance it has less harmonics, add lighter rods and pistons equals less wear at high HP levels. The rod angle ratio with a 5.400 rod is not that extreme.
QUOTE(Mueller @ Jun 13 2006, 09:15 PM)
yep stock heads..that is why I went with the 94mm bore instead of the 96mm bore, the larger bore (and stroke) would benifit or would for sure need head work...this motor would have worked normally asperated or with the small turbo I have..that is how Jake and I had planned it from the start... (still going to install the turbo on my 1.8)...
cool, thanks for the info. I was wondering why you were using a 94mm bore, now I get it. did you have custom long barrell (sp?) cylinders, or very offset wristpins?
(sorry for the hyjack everyone else)
Mike, yes it does. I cannot export the pintout directly, but I will scan it and see if I can post it as a picture. If you have a FAX # I can "print" and send it as a FAX. If you want, send me your fax# to jacquiken@verizon.net or post it here.
It would be nice if somebody on the BBS had a good dyno program. Maybe the Club should buy one and find someway to allow members to use it.
Ken
It would be nice if somebody on the BBS had a good dyno program. Maybe the Club should buy one and find someway to allow members to use it.
Ken
stock Type I pistons (aftermarket) and stock length cylinders (Nickies)...CB performance rods (mod'd by Jake for clearance issues with the cam)
end
QUOTE(Mueller @ Jun 13 2006, 06:15 PM)
Mark, I don't even know where to start....you cannot compare a pushrod V8 in a pedestrian grocery getter to a purpose built V10 barely streetable racecar...as for quoting Jake, I've done quite a bit of homework on the Type IV's and learned from Jake and others (still learning)
I too have learned from MANY, and am still learning. Again, I just offered my opinion. I could still be very wrong. No hard feelings?
Again, to the Porsche/Chevy reference, my point remains valid. Displacement is important, but engineering volumetric efficiency goes a long way in accomplishing your goals. I'll shutup now and give this guy his thread back.
Mark D.
QUOTE(Mueller @ Jun 13 2006, 09:25 PM)
stock Type I pistons (aftermarket) and stock length cylinders (Nickies)...CB performance rods (mod'd by Jake for clearance issues with the cam)
end
Thanks.
over 
QUOTE(jd74914 @ Jun 13 2006, 09:05 PM)
QUOTE(Mueller @ Jun 13 2006, 08:46 PM)
Ken,
The motor I sold to Mark Henry was going to be a 94mm X 78mm engine. (still should be since I think Mark is putting it together with all the components I sold him)...Jake helped me with the selection of components, the idea was that with the stock 2.0 heads I had, the extra stroke and smaller bore would allow the cylinders more time to ingest the air/fuel mixture. With the cam spec'd by Jake, he thought 160hp was not out of the question...very similar to the 2270 posted above, but with the bone stock 2.0 heads, probebly lacking a little here and there....still would have been a fun motor...
Mike, you were going to build it with stock heads? Was this engine planned for turboing (hence extra air being forced in)?
Mike's ex-engine is still in the planing stage....really I'm just busy as hell and won't get to it till late summer. I have 2.0 heads and I'm going with 42X38mm SS valves, the new seats are being cut in now. I "may" sell the balanced crank assy. and get another to do a DTM turbo setup...still thinking and researching on that one. If not I'll just leave it NA and use Mike's crank and stock cooling.
My 102mm nickies are going into my bug with a DTM and an A1 header. Everything is done for that one except the balance and assy.
good dicussion. I'm looking to do something along these lines in the winter and its good to hear all the different takes and options.
QUOTE(Mueller @ Jun 13 2006, 09:25 PM)
stock Type I pistons (aftermarket) and stock length cylinders (Nickies)...CB performance rods (mod'd by Jake for clearance issues with the cam)
end
going to need .300+ of shim under the nickies.
QUOTE(Mark Henry @ Jun 13 2006, 06:47 PM)
QUOTE(Mueller @ Jun 13 2006, 09:25 PM)
stock Type I pistons (aftermarket) and stock length cylinders (Nickies)...CB performance rods (mod'd by Jake for clearance issues with the cam)
end
opps, I guess I would have needed cylinder spacers afterall, hahahhaha
QUOTE(Mark Henry @ Jun 13 2006, 06:19 PM)
OK, but here's the rub.
Just because the stock stroke is shorter it doesn't equal less wear or higher rev's. Stock rods are about 815g and the aftermarket type 1 rods are 590g, so that alone is close to a half pound less being tossed around. If you're using stock pistons they weigh 710g, my 102mm JE's weigh in at 510g (so I expect the 96mm KB, 22mm pin are the same or less) so if your using a stock piston (or KB with a 24mm pin) you're now pushing almost an extra pound per journal. Multiply that pound by 6000rpm
Unless you are using $1200.+ Carrillo rods and $1000. JE 22mm pin pistons you just lost any advantage you may have had from the shorter stroke.
At any rate even if you stick with stock rods you should upgrade to ARP rod bolts so there's $150
Also note in those dyno graphs that both torque and HP are done at 5800rpm, so being able the rev higher doesn't mean a whole lot.
If the 78mm crank is counterweighted, with a proper balance it has less harmonics, add lighter rods and pistons equals less wear at high HP levels. The rod angle ratio with a 5.400 rod is not that extreme.
OK so this is some practical info. Just moving to 96mm pistons may reduce realiablity due to added weight.
Jakes chart shows a pretty good improvement going to a 78mm stroke. The problem is we do not know all the things he did to the 2270 that may not have been in the 2056.
The budget for 78mm is:
Crank $500
96mm 22mm-pin 1.11 KB P&C $375
H Beam T1 22mm rods $275
So it will take about $1150.
BUT, got to buy P&Cs anyway so it will take $775 to go to 78mm.
Humm not to much more unless there are clearence problems that require a lot of machine time.
Jake does not like to talk about exactlly what it take to make things fit - so is there somebody else who might be able to help??
Ken
Add to that the cylinder boring.
This is what I'd do....spend the extra buck. You need the cylinder cores, but it's $550 for the 96 P&C's off of Jake. Rods are only $25 more and clearanced, the crank is about the same price.
Then get the cam and lifters also off of Jake...if you buy the crank etc., from him he'll pick you a nice cam for your needs, plus you know it clears everything and most important it lives.
Then after that you can bargain shop.
This is what I'd do....spend the extra buck. You need the cylinder cores, but it's $550 for the 96 P&C's off of Jake. Rods are only $25 more and clearanced, the crank is about the same price.
Then get the cam and lifters also off of Jake...if you buy the crank etc., from him he'll pick you a nice cam for your needs, plus you know it clears everything and most important it lives.
Then after that you can bargain shop.
How long do these 2270 cc motors last? How many people have them and what kind of streetability do they exhibit? Can you trust a type 1 rod in a setup like that?
QUOTE(Mark Henry @ Jun 13 2006, 07:42 PM)
Add to that the cylinder boring.
KB Pistons only = $229
Bore 94 to 96 by RIMCO(will match to piston) = $135
== $364
Ken
QUOTE(KenH @ Jun 12 2006, 11:23 PM)
In playing with my el-cheapo dyno program it looks like you can get the same HP with either a 71mm or 78mm stroke. The 78mm however gives a bit more torque.
I'm curious about this program. I've done the calculations by hand (thank you very much MAE145), but I have a feeling its a Mathematica/Matlab sort of program that just calculates motion ratios (which is not a bad thing). EVERY good engine has been at this stage in its development, where you have to look at motion ratios along with combustion pressure.
Theres a huge matrix you can put all the equations of motion that compensate for inertia and momentum that can actually solve for torque. It isnt rocket science... well it is, but its easy rocket science.
Why do these motors build torque after the horsepower dies off? Refer to the dyno graphs on page 1.
QUOTE(Thack @ Jun 13 2006, 10:58 PM)
How long do these 2270 cc motors last? How many people have them and what kind of streetability do they exhibit? Can you trust a type 1 rod in a setup like that?
Depends on how hard you are on it, level of performance, etc
I'd say go through it (new bearings, valve job, etc) at 60,000 miles.
The h-beam rods are way stronger than a stock T4 rod.
Ken, Rimco have had a few issues with boring, but they're a good outfit and should have fixed any problems. The rest of the stuff your not saving a whole lot. With all the cam issues going on Jake's cam and lifters are extra bucks that are worth it to me.
The heads and valve train of these motors seems to be a tricky area to get just right.
I think that Jake has spent years on a dyno trying different cams, push rods, and valve sizes to find a combo that he likes...
I think that there is more than just 775 to get the same results that Jake gets on a 2270 motor...
You can lighten the valve train,,,etc all with a simple credit card.
rich
I think that Jake has spent years on a dyno trying different cams, push rods, and valve sizes to find a combo that he likes...
I think that there is more than just 775 to get the same results that Jake gets on a 2270 motor...
You can lighten the valve train,,,etc all with a simple credit card.
rich
QUOTE(Thack @ Jun 13 2006, 08:13 PM)
Why do these motors build torque after the horsepower dies off? Refer to the dyno graphs on page 1.
HP = Torque*RPM/5252
why would it die off?
The 2270 motor clearly attains peaks HP at 4000 rpms and slowly tapers off. Then go up to 6000 rpm where you make best torque but the HP is down to 134 HP. Most other motors make max torque first then rev out to reach max HP.
Matt, your equation is not working with this graph.
Its how Jake builds engines. I wouldnt want one on the track, but it looks fun for the street. This is an engine built for torque only. A high fun factor. Search for his blubonic plague or something (the blue bug). It practically does wheelies it has so much torque, but I'll bet it sucks above 5k rpm.
If you're building a type 4, its going to be for recreational use. I totally believe Jake is on the right track. There are a few guys racing 914-4s, but for the most part, they are hot rods. A race car is going to be built on totally different principals.
If you're building a type 4, its going to be for recreational use. I totally believe Jake is on the right track. There are a few guys racing 914-4s, but for the most part, they are hot rods. A race car is going to be built on totally different principals.
yeah that's wierd...that equation is the standard from what I remember from high school physics.
but doesn't the equation also work if we assume that the torque is in fact dying off after X rpms, which has an inverse relationship with HP.
edit: nevermind I am dumb...
but doesn't the equation also work if we assume that the torque is in fact dying off after X rpms, which has an inverse relationship with HP.
edit: nevermind I am dumb...
QUOTE(Thack @ Jun 13 2006, 08:28 PM)
Matt, your equation is not working with this graph.
As much as I'd like to take credit for the unit of Horsepower, I cant. It is a commonly accepted definition, though. You may want to try a new calculator because it works for me.
I see the problem...
try reading the footnote.
"purple = torque, blue = hp, yellow = fuel"
does that work for you now?
try reading the footnote.
"purple = torque, blue = hp, yellow = fuel"
does that work for you now?
Sorry guys, I see now I read the graph backwards. It was mentioned that this motor reached 160+ HP. Thanks for setting me straight.
QUOTE(r_towle @ Jun 13 2006, 08:16 PM)
The heads and valve train of these motors seems to be a tricky area to get just right.
I think that Jake has spent years on a dyno trying different cams, push rods, and valve sizes to find a combo that he likes...
I think that there is more than just 775 to get the same results that Jake gets on a 2270 motor...
You can lighten the valve train,,,etc all with a simple credit card.
rich
I Jake has done a lot of work to get things optimized.
I do not need to build the ultimate engine just a good engine at a resonable cost with relativly available parts.
I am leaning towards the 78mm crank and buying at least the rods from Jake as he has worked out the "clearence" problems.
His CAM may be a good thing to buy as again it has been optimized for 96x78.
As far as HP vs RPM I have no problem with the HP peaking at 6000. I can match my gearbox to the motor if it means I can get a reliable motor.
Just wish I could resolve the HP vs different stroke issue. Common sense say ther should be a HP gain by using a longer stroke. May have to look at my program again.
Ken
QUOTE(MattR @ Jun 13 2006, 08:36 PM)
If you're building a type 4, its going to be for recreational use. I totally believe Jake is on the right track. There are a few guys racing 914-4s, but for the most part, they are hot rods. A race car is going to be built on totally different principals.
And those Principals are??????
Ken
"And those Principals are??????"
I would think fast reving and engines that stay at mid to high rpm. Lightened rotating mass (flywheels, crank...) and poor idle(because of a big cam tuned for high rpm).
I would think fast reving and engines that stay at mid to high rpm. Lightened rotating mass (flywheels, crank...) and poor idle(because of a big cam tuned for high rpm).
He means that a super torquey engine is great for an around town hot rod. It's got good torque starting at 2,500 rpms so in most any gear you step on the gas it goes. A higher reving engine would be better in a track situation because you spend all of your time at higher revs. Raby's 2316 is a high rever (180hp at 7000rpms):
http://www.aircooledtechnology.com/about_jake_cars.htm#914
If you want hp at higher revs I guess you just choose the right cam.
http://www.aircooledtechnology.com/about_jake_cars.htm#914
If you want hp at higher revs I guess you just choose the right cam.
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