Is the spark plug location and valve sizes that much better on the 2.0 heads compared to 1.8 heads??
The motor in question is going to be turbocharged, so I would think that the size of the valves wouldn't make as much of a difference. The cam also has more than normal lift on the exhaust(or is it duration, I have to look at the specs again)
I know the intake manifold is different, but it's not that big of deal to run the 1.8 runners since they are the same ID as 2.0 runners.
Reason for asking???
I "loaned" out my rebuilt 2.0 heads and know that the person has freshly rebuilt 1.8 heads sitting around.
Full Version: 1.8 verses 2.0 heads.......
Made me think.
1.8 heads are deemed more robust; that's their reputation. Whether this is truly the case or depending on lower strain in 1.8 engines in general I wouldn't know (I drive a 1.8 myself; heads were excellent during a recent engine rebuild).
However, it strikes me as odd and that you say that valve diameter wouldn't matter so much. IMPO it would matter a lot since a turbo significantly increases intake air pressure. A relative obstruction (small intake and/or outlet valves) can become an absolute obstruction (flow will not increase sufficiently) at higher pressures, rendering the turbo useless.
So, to put it another way, I would go for an after-market set up with larger valve diameters, for instance Pauter heads.
1.8 heads are deemed more robust; that's their reputation. Whether this is truly the case or depending on lower strain in 1.8 engines in general I wouldn't know (I drive a 1.8 myself; heads were excellent during a recent engine rebuild).
However, it strikes me as odd and that you say that valve diameter wouldn't matter so much. IMPO it would matter a lot since a turbo significantly increases intake air pressure. A relative obstruction (small intake and/or outlet valves) can become an absolute obstruction (flow will not increase sufficiently) at higher pressures, rendering the turbo useless.
So, to put it another way, I would go for an after-market set up with larger valve diameters, for instance Pauter heads.
Street car, daily driver on pump gas=low boost in the 8-10 pound range
No need for super expensive parts such as those heads
Yes, the 2.0 should have less restriction, but for my application, I don't think it's going to make much of a difference between the two heads.
I was wondering if the valve sizes are also what makes the 2.0 heads tend to crack more since there is less material between the valve seats.
No need for super expensive parts such as those heads
Yes, the 2.0 should have less restriction, but for my application, I don't think it's going to make much of a difference between the two heads.
I was wondering if the valve sizes are also what makes the 2.0 heads tend to crack more since there is less material between the valve seats.
From the Pic those look like square port bus heads anyway?
Same thing I was thinking, about the distance between the valves... Perhaps 1.8 heads are not such a bad choice after all.
I haven't heard of anyone able to compare the two types of heads on one block.
Good luck with your "low pressure turbo"; those Saab 900 drivers sure are getting some competition.
I haven't heard of anyone able to compare the two types of heads on one block.
Good luck with your "low pressure turbo"; those Saab 900 drivers sure are getting some competition.
QUOTE(rdauenhauer @ Sep 24 2003, 10:22 AM)
From the Pic those look like square port bus heads anyway?
True.
They also make 914 heads though.
But it is as Mueller says: $$$
I think that the difference between the 2.0L and 1.8L heads with their small valves is pretty small in a turbo application. The size difference 42x36 vs 41x34 shouldn't be a problem and the increased strengh of the spark plug hole on the 1.8 head is very important. Turbo motors can run very hot and I think the 2.0L heads wouldn't be the best choice due to their weakness. I guess you could weld up the spark plug hole and go to the smaller plug to correct this. The difference in flow between the 2 heads is considerable but exactly how much? I don't remember the numbers. Maybe Jake Raby will comment as he has done the testing.
I think you want as much low end torque in the motor to lessen the effects of turbo lag. Lots of low end grunt to get you going until you hit the higher revs when the turbo kicks in is important. Otherwise you will have to size the turbo smaller to minimize turbo lag. Course that will effect the top end power with the smaller turbo. I know you are not going to run stock compression ratios so that will also cut into your hp/torque at low rpms.
Take Blairs RX7 turbo2 car now. It has excellent low end power and drives nicely in the low rev range just like a normal car. Step on the gas and it acts like a normal car with lots of torque. When you hit the boost rev range (about 3000) , the ("Holy shit") hp comes on strongly until you hit the rev limiter (7500 at 15lbs).
With a 914 motor unless you have set the motor up to rev over 6500, you will have to get all your boost and power in the lower rpm ranges (3000-6000). I think you will be able to supply all the boost you want, say up to 15lbs. I think the problem is to keep the engine cool enough so it doesn't melt down. If you only plan on low boost , 5 lbs, your problems will stay small.
Do you on running a large front oil cooler? Maybe with a electric fan for extra cooling at low speeds?
EFI that you can control the A/F maps, especially in small 500 rpms steps?
Rising rate fuel pressure regulator?
Geoff
I think you want as much low end torque in the motor to lessen the effects of turbo lag. Lots of low end grunt to get you going until you hit the higher revs when the turbo kicks in is important. Otherwise you will have to size the turbo smaller to minimize turbo lag. Course that will effect the top end power with the smaller turbo. I know you are not going to run stock compression ratios so that will also cut into your hp/torque at low rpms.
Take Blairs RX7 turbo2 car now. It has excellent low end power and drives nicely in the low rev range just like a normal car. Step on the gas and it acts like a normal car with lots of torque. When you hit the boost rev range (about 3000) , the ("Holy shit") hp comes on strongly until you hit the rev limiter (7500 at 15lbs).
With a 914 motor unless you have set the motor up to rev over 6500, you will have to get all your boost and power in the lower rpm ranges (3000-6000). I think you will be able to supply all the boost you want, say up to 15lbs. I think the problem is to keep the engine cool enough so it doesn't melt down. If you only plan on low boost , 5 lbs, your problems will stay small.
Do you on running a large front oil cooler? Maybe with a electric fan for extra cooling at low speeds?
EFI that you can control the A/F maps, especially in small 500 rpms steps?
Rising rate fuel pressure regulator?
Geoff
QUOTE(Mueller @ Sep 24 2003, 08:40 AM)
The cam also has more than normal lift on the exhaust(or is it duration, I have to look at the specs again)
Yeah, high lift low duration.. Don't want to blow through.
-Aaron G.
Those Pauter heads are pretty, but what about a header? Those are Type1 exhaust ports location which come out the front and back of the head, not down to the bottom.
How you gonna do dat??
Paul
How you gonna do dat??
Paul
QUOTE(Mueller @ Sep 24 2003, 10:08 AM)
Street car, daily driver on pump gas=low boost in the 8-10 pound range
No need for super expensive parts such as those heads
Yes, the 2.0 should have less restriction, but for my application, I don't think it's going to make much of a difference between the two heads.
I was wondering if the valve sizes are also what makes the 2.0 heads tend to crack more since there is less material between the valve seats.
No need for super expensive parts such as those heads
Yes, the 2.0 should have less restriction, but for my application, I don't think it's going to make much of a difference between the two heads.
I was wondering if the valve sizes are also what makes the 2.0 heads tend to crack more since there is less material between the valve seats.
CB Performance sells a book called "Turbomania" that might be of some use to you and if you don't already have it, you might want to buy the Engine Analyzer software to help you design the motor. Wasn't the 944 turbo only 2 valves/cylinder?
"Turbomania" is a good book if you don't have it. The book even has a picture of Bernie Bergmans bolt on Turbo kit (upto 5lbs.)
Since you are staying below 10 lbs I don't think you will have too many problems other than the oil temps.
Geoff
Since you are staying below 10 lbs I don't think you will have too many problems other than the oil temps.
Geoff
I've got all the turbo books........good info, but still nothing about my original question
One of the big differences is the sodium valves on the 2.0. From what I understand - this helps conduct heat away better. This might be a concern with a turbo setup.
I was thinking of doing exactly the same thing, but then I decided to use another Volkswagen derived 4 cylinder turbocharged boxer engine that puts out slightly more power :-).
One guy I spoke to at a PCA autocross was talking about one problem with type IV engines being that it's hard to keep the heads on with a turbo setup, which is one thing the type 1 motor apparently has over the type IV. He also suggested getting the heads flycut to accept 2.0 cylinders and using Bus P&Cs to get up to about 19xx ccs. I thought that this might make a good turbo motor. He reckoned that you wouldn't want to get the boost much above 10psi before things would start to fall apart.
IMHO the valve sizes will make less of a difference with a turbo motor because everything is being forced harder, so you should be fine.
Fiid.
I was thinking of doing exactly the same thing, but then I decided to use another Volkswagen derived 4 cylinder turbocharged boxer engine that puts out slightly more power :-).
One guy I spoke to at a PCA autocross was talking about one problem with type IV engines being that it's hard to keep the heads on with a turbo setup, which is one thing the type 1 motor apparently has over the type IV. He also suggested getting the heads flycut to accept 2.0 cylinders and using Bus P&Cs to get up to about 19xx ccs. I thought that this might make a good turbo motor. He reckoned that you wouldn't want to get the boost much above 10psi before things would start to fall apart.
IMHO the valve sizes will make less of a difference with a turbo motor because everything is being forced harder, so you should be fine.
Fiid.
I don't think the slightly smaller valves of the 1.8 head are gonna hurt you if you run a turbo. And since the 1.8 heads seem to handle heat better, it might be a smart choice.
Like Alfred said, the 944 and even 968 turbo engines used 8 valves instead of 16
Ofcourse a complete different animal and I think they run at 1.0 bar boost, but I believe turbo engines in general are a lot less sensible in this matter since the pressure will pump the air into the combustion chamber anyway
And since your way in over your head anyway, why not build a bi-turbo setup. Use 2 small turbo's from one of those small Japanese or Korean 1.0L engines or from a Smart
But then again... WTF do I know about this stuff anyway
and everybody knows you can't turbo a 914
cheers,
Jeroen
Like Alfred said, the 944 and even 968 turbo engines used 8 valves instead of 16
Ofcourse a complete different animal and I think they run at 1.0 bar boost, but I believe turbo engines in general are a lot less sensible in this matter since the pressure will pump the air into the combustion chamber anyway
And since your way in over your head anyway, why not build a bi-turbo setup. Use 2 small turbo's from one of those small Japanese or Korean 1.0L engines or from a Smart
But then again... WTF do I know about this stuff anyway
and everybody knows you can't turbo a 914
cheers,
Jeroen
Conventional wisdom and the fact that most people are complete wusses says you can't turbocharge it.
I don't see a reason why you can't. People have built big-4s with pretty high output - so if you assume that the heat output is the same (which is probably an utterly crap assumption)- a low boost turbo set-up ought to be able to put out some reasonable (120 - 140 hp? more?) power out and still be able to cool itself. Of course - you may want to go to an external cooler, and maybe go to a more extreme cooling setup, but it ought to be possible to build a decen't motor.
I did run the numbers though and found that it probably wouldn't be feasable to get more than 100hp from a 1.7 with a blower.
The thing to remember is that turbos aren't only used in 20psi hotrod motors.... a lot of applications are only used for atmospheric compensation (such as aircraft motors). So the question remains - how much boost can you run in a type IV and have it run nicely.
This is a topic of great personal debate for me, so I am interested in other opinions.
Fiid.
I don't see a reason why you can't. People have built big-4s with pretty high output - so if you assume that the heat output is the same (which is probably an utterly crap assumption)- a low boost turbo set-up ought to be able to put out some reasonable (120 - 140 hp? more?) power out and still be able to cool itself. Of course - you may want to go to an external cooler, and maybe go to a more extreme cooling setup, but it ought to be possible to build a decen't motor.
I did run the numbers though and found that it probably wouldn't be feasable to get more than 100hp from a 1.7 with a blower.
The thing to remember is that turbos aren't only used in 20psi hotrod motors.... a lot of applications are only used for atmospheric compensation (such as aircraft motors). So the question remains - how much boost can you run in a type IV and have it run nicely.
This is a topic of great personal debate for me, so I am interested in other opinions.
Fiid.
Maybe someone could hack into Porsche's computers and steal the info or at least ask some of the engineers to come here and play with us.
that's a vintage ad! I don't think they have a type-4 turbo kit anymore....
I don't know a lot about 1.8 v. 2.0 heads... but the 1.8 does have a larger combustion chamber... which should be helpful in a turbo'd motor... I would think...
I don't know a lot about 1.8 v. 2.0 heads... but the 1.8 does have a larger combustion chamber... which should be helpful in a turbo'd motor... I would think...
I think you should use the 1.8l heads and also have a flame seal cut into the head/cylinder seating area. This will help seal the head and cylinder and prevent leakage under boost.
Geoff
Geoff
Mike a couple of things…
Our buddy Rich…you know who…runs 1.8 heads with ‘substantial headwork’…there surely must be a reason…
Jake apparently welds up the spark hole and redrills a smaller diameter spark plug to give more material there…to minimize/avoid cracking.
For a Turbo, don’t you want the lowest compression possible to start with…Like a 73 1.7 EB code? The 1.7 L heads would have more material to work with and I think its 8.2:1…Gee I have one of those available wouldn’t you know…
Our buddy Rich…you know who…runs 1.8 heads with ‘substantial headwork’…there surely must be a reason…
Jake apparently welds up the spark hole and redrills a smaller diameter spark plug to give more material there…to minimize/avoid cracking.
For a Turbo, don’t you want the lowest compression possible to start with…Like a 73 1.7 EB code? The 1.7 L heads would have more material to work with and I think its 8.2:1…Gee I have one of those available wouldn’t you know…
when a 2.0 heads is flowed Vs a 1.8 the numbers are close to the same with stock ports......but the plug location and chamber design have yielded me a 10% power increase on almost every engine I have done exactly the same with 1800 and 2.0 heads.
The 2.0 heads have weak chambers, but I know the way around that!
All my strongest engines get 2.0 914 heads.
The 2.0 heads have weak chambers, but I know the way around that!
All my strongest engines get 2.0 914 heads.
I believe the 1.8's have larger combustion chambers than 1.7's but smaller than 2.0's
I think there is a big improvement in the exhaust ports in the evolution. the 1.7's are very small, the 2.0's are much more open.
But of course, I would defer to Jake's knowledge.
I think there is a big improvement in the exhaust ports in the evolution. the 1.7's are very small, the 2.0's are much more open.
But of course, I would defer to Jake's knowledge.
Jeff,
Rich uses 1.8 heads because of the class we run in SCCA road racing. We also have to run stock valves (granted they are being lifted off the seat by some .625) Look down the intake some time when the intake valve is open on the race engines... you cant even see the "tulip" of the valve when its at peak lift. All you see is stem.
B
Rich uses 1.8 heads because of the class we run in SCCA road racing. We also have to run stock valves (granted they are being lifted off the seat by some .625) Look down the intake some time when the intake valve is open on the race engines... you cant even see the "tulip" of the valve when its at peak lift. All you see is stem.
B
On all the F Production engines I have worked with, and re configured I use LESS lift and more duration. It keeps the valvetrain together MUCH longer. One customer snapped 4 valves off in one season before he came to me. This is his seconmd season and no snapped valves, and one race away from the championship.
Alot of lift is hard on the valve train, and normally only gains down low power, something not needed with an engine that sees 4-8000 rpm as a powerband.
Alot of lift is hard on the valve train, and normally only gains down low power, something not needed with an engine that sees 4-8000 rpm as a powerband.
Hopefully I can add some info to this discussion when my 2.0 heads come back from adrian. I had my port work floed so I can tell you what modified 2.0 914 heads do. As sson as I get my adapter made up I will test some 1.8 heads and let you know. I am prototyping some welded and heavily modified heads now. Will share some info on those as they progress.
AS far as the stock heads go keep this in mind. Porsche developed the 2.0 heads and VW developed the 1.8 heads. The mindsets of the two companies were totally different.
With a turbo, the stock heads tend to flex alot. Even with six studs. 14psi is the range when the heads with stock 4 studs tend to start moving. If your going to run minimal boost why bother with a turbo motor. If you really want to make some serious power then go turbo and do the developement work, right.
Sa far as valve train goes, turbo cams run less duration and similar or more lift than there NA cousins. Open the exhaust valve a little sooner and you can mimize lag. With regards to the FP motors, If you are breaking the heads off the valves you need to talk to your cam grinder and perhaps do a little work with a spintron. How agressive the rear ramps on a cam are determines the load on a valve, unless you are floating the valves or bouncing them off the seats. Harmonics in a race engine can be very destructive but the resonant range of the valve train materials can determine where those bad harmonics occur. In some cases if you lower your rpm you can do more damage to valve train than by spinning the engine higher. It all depends on where the harmonics occur. Jake the reason your customer kept breaking valves is because he over revved or floated the valves to often. Valves don't necessarily float at redline.
AS far as the stock heads go keep this in mind. Porsche developed the 2.0 heads and VW developed the 1.8 heads. The mindsets of the two companies were totally different.
With a turbo, the stock heads tend to flex alot. Even with six studs. 14psi is the range when the heads with stock 4 studs tend to start moving. If your going to run minimal boost why bother with a turbo motor. If you really want to make some serious power then go turbo and do the developement work, right.
Sa far as valve train goes, turbo cams run less duration and similar or more lift than there NA cousins. Open the exhaust valve a little sooner and you can mimize lag. With regards to the FP motors, If you are breaking the heads off the valves you need to talk to your cam grinder and perhaps do a little work with a spintron. How agressive the rear ramps on a cam are determines the load on a valve, unless you are floating the valves or bouncing them off the seats. Harmonics in a race engine can be very destructive but the resonant range of the valve train materials can determine where those bad harmonics occur. In some cases if you lower your rpm you can do more damage to valve train than by spinning the engine higher. It all depends on where the harmonics occur. Jake the reason your customer kept breaking valves is because he over revved or floated the valves to often. Valves don't necessarily float at redline.
Jake you'll have to talk with David Finch about the lift thing.. The cam is a variation of his work in the past. The engines last a full season and then are pulled apart for freshening (7 customers running the same engine) they dont seam to have a problem. One customer likes to run the carbs a little lean and he was blowing up pistons.. but it didnt have anything to do with the valve trane.
B
B
I think the blue car was up to 14psi. At some point jeff will have to actualy put his new motor togather so it we can see what it'll do without 150k miles on the motor and only 3 exhaust studs.
-Aaron G>
-Aaron G>
So where is Jeff? Good to see you here Aaron but I miss the Jeff's turbo posts.
Geoff
Geoff
QUOTE(Bleyseng @ Sep 25 2003, 11:31 AM)
So where is Jeff? Good to see you here Aaron but I miss the Jeff's turbo posts.
Geoff
Geoff
He's a lazy ass. When he gets back to work on his car he'll come back.
-Aaron G>
He also doesn't have internet at work
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