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Discussion Starter · #1 ·
Hi Everyone. I have been tuning the Jalpa and have a Dyno session scheduled for Thursday. I put a couple of bungs in and am using a wideband o2 sensor for mixture. I went to do a 0-60 pass and a 0 to 100 pass today. The problem I have from a standing start is that the clutch slips and it will not hold all the torque the engine is generating. I have 335/17 tires with a soft compound so they really stick. When I floor it the clutch slips for about 2 seconds as I start moving. I bought a sachs performance clutch but am using the stock pressure plate. It is obviously inadequate. I hit 0 to 80 in 10 seconds until a car pulled out in front of me.(Losing 2 seconds for clutch slip)Probably would have taken 3 or 4 more seconds to hit 100. It pulls really hard at higher speed. What has everyone done to improve the clutch hold? Does anyone make a better pressure plate or can rebuild one to make it better.
 

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These are my clutch components.

The information on the pressure plate should be visible in the picture and the disc I got in 2003 from Centerforce (Midway Industries, Centerforce Customer Service, 2266 Crosswind Dr., Prescott, AZ 86301)

The clutch feels very solid and I can chirp the tires (265/45-16, Kumho v710) without clutch slippage from a standstill.

Laust
 

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Discussion Starter · #3 ·
Thanks Laust, Were you having the same problem before? I bought the Sachs performance clutch but the stock pressure plate is way too weak I think. I will check that out. Any Idea how much torque yours is making?
 

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Hi Lee,

I have never had a clutch slipping problem on my Jalpa, but the clutch upgrade was part of preparing for the turbo upgrade in anticipation of more torque. I don't know the actual number, but the peak boost is the in the 12-15 psi range, comes in at around 3000rpm and the engine is very healthy.

In the search for the pictures I found my 2003 letter to Centerforce and got reminded that I sent them the flywheel, the pressure plate and the disc (I believe all OE) and asked for at least 500 ft-lb torque handling capacity and mentioned that I could tolerate a doubling of the pedal (and therefore clamping) pressure. I received all 3 components back, but when calling the customer service person about the numerical results (500 ft-lb torque handling capacity) he could not give me an answer. I took a chance, installed the components and have been fully saticfied with the result ... no hint of slippage and very tolerable pedal pressure (50 lbs with the OE hydraulics).

Laust
 

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Discussion Starter · #5 ·
Thanks. That is great info. Can you post their contact info or PM me. I will send mine off when I pull it out. Sounds perfect. I should know tomorrow how much torque mine is making.
 

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Discussion Starter · #6 ·
Hey Laust. What kind of 0 to 100 does yours do?
 

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Thanks. That is great info. Can you post their contact info or PM me. I will send mine off when I pull it out. Sounds perfect. I should know tomorrow how much torque mine is making.
Look at post #2, but let me add their phone numbers also, namely (928) 771-8422 and (800) 932-5882.
 

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Discussion Starter · #8 ·
Went to the dyno today. Here are the Wheel results . It is making 244.38 Wheel Hp and 225.44 Ft Lbs of torque The dyno guy translated to engine HP 305 and torque 281 ft lbs
Pretty good increase over stock 255 HP and 230 ft lbs. I have a video of it on the dyno but don't know how to upload.
 

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Went to the dyno today. Here are the Wheel results . It is making 244.38 Wheel Hp and 225.44 Ft Lbs of torque The dyno guy translated to engine HP 305 and torque 281 ft lbs
Pretty good increase over stock 255 HP and 230 ft lbs. I have a video of it on the dyno but don't know how to upload.
That is very impressive and it looks like you could even get a little more out of it by making the mixture a little richer, taking the AFR from 13 to 12.

With respect to the video, you could create a YouYube account (if you don't have one already), upload it there and reference it here.
 

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Having spent some 50+ hours with P-250, P-300 and 3.5 L motors on the dyno…the 3.5 liter just last year…the dyno corrections are inaccurate !

The Lamborghini transaxle is one of the better ones in terms of power loss…around 10-11% not 25% !

So the motor is making at best 270 HP at the flywheel !

Paul
 

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Discussion Starter · #11 ·
Thanks Paul. I was just using the formula the dyno guy gave me. Laust I was going to go fatter but only had jets up to 160 so was limited.
 

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Discussion Starter · #12 · (Edited)
Hey Paul,
Do you have any of the dyno charts from those? I would love to see what other engines are doing.PS Guys remember I am only running 8.5 to 1 compression since I was planning to turbo. If I keep it NA, I will have some cams made and raise the compression up to 11 or so . That should help a lot.
 

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I don’t have access to any files, but I can relate the 3.5 Jalpa story. The car was in Belgium 10 years ago with a broken motor, and a guy in Austria bought it.

He approached a friend and later me for a re-build, but we declined. He subsequently found a guy in Germany who had allegedly built 20 or 30 Lambo motors.

It appeared that the builder was an “originality freak” and proceeded to build a motor much like a Lambo factory assembler might have done in 1986.

No modern methods, dynamic balancing, oil galley / compression modifications etc. and… using only OEM parts like matched piston/liners etc.

This project became very expensive…so the (bill-payer) asked for a dyno test.

The motor after much huffing and puffing made about 234 HP (I did not witness final runs).

This is not unrealistic… since a 3 liter motor in OEM configuration does 220 HP

Paul
 

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Discussion Starter · #14 · (Edited)
So what are the real numbers for a stock Jalpa? Do you think the 234 is realistic. I know lambo said 255 or 245 depending on which you read. Everyone says that was optimistic. I wonder how much I increased over stock. 15% ? 20% ? The heads flowed about 25% over stock. However I left the CR low planning to Turbo. Do you remember how much your built engines were making? The 300 or 3.5. I am wondering how much power I could make with custom cams, custom heads and about a 9 k redline. If I open the engine again, I am going for every pony in there. May keep Normally aspirated just for fun.
 

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Based on our work, a stock (assembled by Lambo) 3.5 L motor is around 225 HP…so 234 HP is clearly better than “stock”.

Compression from 9:1 to 11:1 is a gain of 15-20 HP

Cams for street use can go to… as I recall just around 11 mm of lift (.440”)

I would not touch the heads since your port work could hurt the motor in terms of power under 6500 rpm.

As I have mentioned in the past we ran a cylinder head (valves/cams) to 8800 rpm…BUT

I don’t think that the lower end (crank, oil supply, oil pick-up) can handle anything over 7500 rpm reliably... without serious re-work.

Paul
 

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I don’t think that the lower end (crank, oil supply, oil pick-up) can handle anything over 7500 rpm reliably... without serious re-work.
Paul
Correct, they lowered the rpm Limit from 7400 to 7000 after having issues.
 

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Discussion Starter · #17 ·
Do you know what issues they were having? It would be interesting to see if I corrected some of those when I rebuilt. I had the rods deburred, shot peened, bronze bushings installed and arp bolts. The crank appears capable of plenty of power and rpm. I also added ARP head studs and run much more torque than stock. Better gaskets as well. Were the problems valve train or bottom end?
 

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From what I was told they had broken rods.
 

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Discussion Starter · #20 ·
The rods seemed pretty good just needed working. The bolts were not that great. I wonder if it was the rods themselves or bolt failure. Hey Chris, Diablo Clyde flew down this week from Washington and drove the Jalpa. Really liked it. He said he knew sledge but had not seen your car. Nice guy . You should try and meet up with him. I would love some feedback on how mine drives compared to a stock one.
 
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