 Engine choice for Autocross, Just some thoughts |
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| Joe Ricard |
 Nov 9 2006, 05:49 PM
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#1
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CUMONIWANNARACEU  Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92  |
So I was listening to Jake's radio show lastnight pt II of the Cylinder heads and power over 120 and up.
I heard him say 2270 makes power to 6 grand followed by 2056 with same heads will make power to 7 grand. So I am building a 2098 71mm stoke 97 mm pistons 10 to 1 compression Probably going to spring for the LE 200 heads Ok so Autocross course of late require me to spin to at least 6250 RPM or shift to next higher gear for that short 40 - 50 feet. Better to stay in lower gear and gut it out against the rev limiter Which is faster overall 2270 that will pull taller gear or accelerate quicker in lower gear but be limited in top speed by being all out by 6K RPM? making 60 MPH tops Or short stroke motor that will pull well with a ZD 3rd and can hit near 70 MPH I think there is more to discuss but I am somewhat distracted right now damn ADD. |
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| URY914 |
Nov 9 2006, 06:02 PM
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#2
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I built the lightest 914 in the history of mankind. Group: Members Posts: 120,236 Joined: 3-February 03 From: Jacksonville, FL Member No.: 222 Region Association: None |
Damn Joe, how about asking a question that can be answered. (IMG:style_emoticons/default/biggrin.gif)
Easy really, you need two engines. After you walk the course, figure out which one works the best for the course layout and stick it in. (IMG:style_emoticons/default/aktion035.gif) |
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| Crazyhippy |
Nov 9 2006, 06:07 PM
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#3
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Insert witty comment here... Group: Members Posts: 1,659 Joined: 28-July 05 From: Home of the Coyotes, AZ Member No.: 4,493 Region Association: None |
running out of power, and running out of revs are 2 different things...
The 2270 should still pull to 6500, but the power will have dropped off @ 6K, thus no shift needed still. |
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| Joe Ricard |
Nov 9 2006, 06:28 PM
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#4
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Don't like should
I like will. Paul I am also curious about the charateristics of your 2316. I imagine your light car can accelerate pretty quickly. do you have stock gears in your transaxle? What kind of RPM's do you pull. Oh and good luck this weekend on the course. |
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| J P Stein |
Nov 9 2006, 06:30 PM
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#5
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Irrelevant old fart Group: Members Posts: 8,797 Joined: 30-December 02 From: Vancouver, WA Member No.: 45 Region Association: None |
Humm.....a couple of items that you may find useful.
Fer instance, my limiter is set at 7100....I could throw in a 7300 or 7500 rpm pill if I ever feel the need. I've used the 7300 but not the 7500. Max power for my cams is around 6300, but that don't mean it's not pulling hard at 7K. Gears rule. A GA mainshaft will get you more speed. I can get 63+ in 2nd at 7100 with these small dia tires. A 904 mainshaft would be nicer, but $$$$$. The B 1st works well for start sections. I was afraid it would kill accelleration...not....shoulda gone to a C. I have found that when I run out of second in a stretch that puts me 30-50 feet from a braking point, a short shift into 3rd is the hot ticket. A bigger motor allows you to "torque thru" a section that you would normaly run in 2nd. This can be a bit hard on the clutch tho.....a down shift to no2 is a piece of cake...if ya geterdone before turning in. (IMG:style_emoticons/default/biggrin.gif) All this is a long way of saying go for the torque. |
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| URY914 |
Nov 9 2006, 07:33 PM
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#6
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I built the lightest 914 in the history of mankind. Group: Members Posts: 120,236 Joined: 3-February 03 From: Jacksonville, FL Member No.: 222 Region Association: None |
QUOTE(Joe Ricard @ Nov 9 2006, 04:28 PM)  Don't like should I like will. Paul I am also curious about the charateristics of your 2316. I imagine your light car can accelerate pretty quickly. do you have stock gears in your transaxle? What kind of RPM's do you pull. Oh and good luck this weekend on the course. My tranny is full of stock gears. I haven't seen a need to change them. I'm waiting for a course layout that makes it better for me to start in 2nd gear. I know I have the torque to do it if needed. My power band is so broad I could get away with only a 2nd and a 3rd really. I try not to go over 6800 but it's seen 7200 or maybe higher before. By the time I hit 7000 I'm looking at the cones, not at the tach. Things happen in my car VERY quickly. (IMG:style_emoticons/default/driving.gif) |
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| Randal |
Nov 9 2006, 07:38 PM
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#7
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Advanced Member Group: Members Posts: 4,446 Joined: 29-May 03 From: Los Altos, CA Member No.: 750 |
QUOTE(J P Stein @ Nov 9 2006, 04:30 PM) Humm.....a couple of items that you may find useful. Fer instance, my limiter is set at 7100....I could throw in a 7300 or 7500 rpm pill if I ever feel the need. I've used the 7300 but not the 7500. Max power for my cams is around 6300, but that don't mean it's not pulling hard at 7K. Gears rule. A GA mainshaft will get you more speed. I can get 63+ in 2nd at 7100 with these small dia tires. A 904 mainshaft would be nicer, but $$$$$. The B 1st works well for start sections. I was afraid it would kill accelleration...not....shoulda gone to a C. I have found that when I run out of second in a stretch that puts me 30-50 feet from a braking point, a short shift into 3rd is the hot ticket. A bigger motor allows you to "torque thru" a section that you would normaly run in 2nd. This can be a bit hard on the clutch tho.....a down shift to no2 is a piece of cake...if ya geterdone before turning in. (IMG:style_emoticons/default/biggrin.gif) All this is a long way of saying go for the torque. Hell JP you're giving away all the secrets. Isn't it better to have the newbies show up with two motors and transmissions? (IMG:style_emoticons/default/happy11.gif) |
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| J P Stein |
Nov 9 2006, 08:35 PM
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#8
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Irrelevant old fart Group: Members Posts: 8,797 Joined: 30-December 02 From: Vancouver, WA Member No.: 45 Region Association: None |
[quote name='Randal' date='Nov 9 2006, 05:38 PM' post='813040']
[quote name='J P Stein' post='812994' date='Nov 9 2006, 04:30 PM'] Hell JP you're giving away all the secrets. Isn't it better to have the newbies show up with two motors and transmissions? (IMG:style_emoticons/default/happy11.gif) [/quote] I gots a soft spot for guys with yellow 914s (IMG:style_emoticons/default/confused24.gif) |
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| grantsfo |
Nov 10 2006, 12:34 AM
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#9
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Arrrrhhhh! Group: Members Posts: 4,327 Joined: 16-March 03 Member No.: 433 Region Association: None |
Torque, torque and more torque.
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| Joe Ricard |
Nov 10 2006, 11:01 AM
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#10
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Wish I would have had the opportunity to drive Fred Hurst's 2270.
Pretty much a street car on street car tires. not sure if I could have used his power of not. He claims 150 as it is an early kit. |
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| anthony |
Nov 12 2006, 04:49 PM
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#11
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2270 club Group: Benefactors Posts: 3,107 Joined: 1-February 03 From: SF Bay Area, CA Member No.: 218  |
Why a 2098? Class rules?
It seems like the ultimate AX motor would be some hybrid of Jake's 2270 Torquer and the 2316. |
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| Joe Ricard |
Nov 12 2006, 07:24 PM
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#12
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
No class rules exactly. just scored the super duper light weight domed 97mm pistons from Paul. and some waterboxster rods from Jake and flywheel clutch, cam lifters from Brett.
looking at 10:1 compression spin to 7000 RPM. and sub 1800 pounds. ZD 3rd gear. LE 200 heads are in my future. TWM throttle bodies and some sort of Fuel injection. Building the fastest car I can with the budget I have. |
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| PinetreePorsche |
Nov 12 2006, 08:18 PM
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#13
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Member Group: Members Posts: 235 Joined: 14-November 05 From: Falls Church, VA Member No.: 5,124 |
Joe R. got my attention with the reference to Jake on a radio show (Jake's show?). Where is it found--of the airwaves, or also on the computer? How long has this been available (sorry to have missed the stream of experience that has run past)? I wanna catch it--is it weekly, or what? -Chris H (PinetreePorsche)
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| Borderline |
Nov 12 2006, 09:24 PM
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#14
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Senior Member Group: Members Posts: 720 Joined: 8-February 05 From: San Juan Bautista, CA Member No.: 3,577 Region Association: Northern California |
Pinetree: go to the Jake's aircooled site and look for the 4th Dimension radio show. they do 1 a week. some very good info and some good deals too.
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| Mike T |
Nov 13 2006, 08:53 AM
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#15
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can't 'member Group: Members Posts: 378 Joined: 16-January 03 From: Brackney, PA Member No.: 161 |
Joe;
I think you would like a "flipped" 5th gear in your 3rd spot in your transaxle. In a way it gives you 2 "second" gears to choose from. I was immediately faster when I had mine done. Figures out to 1.409:1 and is good for 73mph at 6500rpm with 23.5" tires. Now I use 2nd gear on only the very tightest courses. Mike T |
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| Joe Ricard |
Nov 13 2006, 10:29 AM
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#16
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Thanks Mike. You are right I DO love the ZD 3rd.
I have had it in my car for over a year. and my 22 x 9.5 x x15 tires provides awesome acceleration. although top speed is a bit lacking. I am considering an S gear for 4th also. |
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| Mike T |
Nov 13 2006, 12:55 PM
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#17
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can't 'member Group: Members Posts: 378 Joined: 16-January 03 From: Brackney, PA Member No.: 161 |
I didn't realize you already had the ZD setup.
Your 22.5" tires make 2nd good for about 52mph at 6500rpm and a 1750rpm drop when you shift to 3rd. Ever try running a fast 2nd gear course in 3rd? I did that and was faster right away. I was holding myself back by staying in 2nd gear all the time. I realized I could have used 3rd more often than I was. Mike T |
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| Joe Ricard |
Nov 13 2006, 02:34 PM
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#18
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
QUOTE(Mike T @ Nov 13 2006, 12:55 PM) I didn't realize you already had the ZD setup. Your 22.5" tires make 2nd good for about 52mph at 6500rpm and a 1750rpm drop when you shift to 3rd. Ever try running a fast 2nd gear course in 3rd? I did that and was faster right away. I was holding myself back by staying in 2nd gear all the time. I realized I could have used 3rd more often than I was. Mike T Geesh and my 22 inch tires make the ratio even lower. Yea, I have tried short shifting to 3rd @ say 5000 RPM's and the car pulled pretty hard. This was the origin of this thread. to shift or not to shift and weather a high winding motor wouold be better than a torque monster slinging a big ass crank. I guess I didn't realize that a 2270 will also rev to 7 grand. just the way I was listening to it a 2270 was all done by 6 grand. Yea torque is cool. maybe next motor will be 2316 roller motor. (IMG:style_emoticons/default/drooley.gif) |
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| Mike T |
Nov 16 2006, 03:49 PM
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#19
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can't 'member Group: Members Posts: 378 Joined: 16-January 03 From: Brackney, PA Member No.: 161 |
What tires are you running on your car? I thought they were the Formula Atlantic fronts? 22.5x9.5-15. No?
Mike T |
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| Joe Ricard |
Nov 16 2006, 07:16 PM
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#20
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
QUOTE(Mike T @ Nov 16 2006, 03:49 PM) What tires are you running on your car? I thought they were the Formula Atlantic fronts? 22.5x9.5-15. No? Mike T 22 x 9.5 x 15 C3000 Hoosiers R25A I will be getting another set of these as the grip is awesome and got 100 competative runs from them. |
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