LT-5 GT1 engine

[LGAFF]

Can someone ask Graham about the lifters noted below? After reading about the Ford, wondering if he knows any Free HP tricks....


Cylinder heads by Lingenfelter Performance Engineering with D port configuration, no port throttles. Stainless values by Tech Del, titanium value spring seats and retainers and billet steel camshafts. Hydraulic lifters from Audi A8 (different bleed rate from stock to delay the onset of value flow). Cosworth forged pistons with 3mm race piston rings, cast iron liners, 5998cc capacity. Stock throw crankshaft, flat plain configuration. Pace dry sump pump, special oil pan and windage tray, special water pump, higher flow rate. Single mass alloy flywheel, twin plate race clutch.
http://www.corvetteclips.co.uk/images/ZR1/Jeals_tm2.jpg (http://www.corvetteclips.co.uk/site%20pics/ZR1/Jeals.JPG)http://www.corvetteclips.co.uk/images/ZR1/jeals2_tm1.jpg (http://www.corvetteclips.co.uk/site%20pics/ZR1/jeals2.JPG)
The original power curve data shows 615 bhp with two 36mm restrictors (the way it needed to run in the car) in the airbox intake and 645 bhp unrestricted. Max power is around the 7000 rpm mark, max torque of 580 ft/lbs is around 6200 rpm (over 450 ft/lbs at 1200 rpm), red line at 7800 rpm. The team that originally ran Bosh EMS but we will run Motec.
This configuration is how the cars ran in the 97/98 FIA Sports Car Series and the Le Mans 24 Hour races of those years. This engine has around 20 miles of use since a complete re-build and was a spare engine for the team.
This will be probably be going into Geoff's ZR1 which already weighs considerably less than a stock car.

[LGAFF]

Ever wonder what a LT-5 sounds like with a flat plane crank:

http://www.youtube.com/watch?v=gvj74DcKMOI


http://www.youtube.com/watch?v=YzPDe0JbrrU&feature=related

[tpepmeie]

Stock throw crankshaft, flat plain configuration

That crank was not quite stock throw, but rather 92.4mm. Only way to stay under the 6L limit with 4" bores.

[bdw18_123]

Ever wonder what a LT-5 sounds like with a flat plane crank:

http://www.youtube.com/watch?v=gvj74DcKMOI


http://www.youtube.com/watch?v=YzPDe0JbrrU&feature=related


Wow, that thing sounds wicked awesome in the first video! That's an LT5 in that car? Or just a similar DOHC V8? What exactly is a "flat plane crank"?

[LGAFF]

RAcing GT1s had an LT5

Flat Plane crank described below, basicly the crank has no offset of pistons, they are all on the same plane.

http://www.projectm71.com/Cross_FlatPlane.htm

[USAFPILOT]

We should all switch to the flat plane crank

[bdw18_123]

RAcing GT1s had an LT5

Flat Plane crank described below, basicly the crank has no offset of pistons, they are all on the same plane.

http://www.projectm71.com/Cross_FlatPlane.htm

Very interesting, thanks for posting that LGAFF! Learned something new today! :mrgreen:

A flat plane crank LT5 definitely has a unique sound. A real screamer! What is the rev limit on it? I would think it would have to be as high as maybe 10K since (from the info you posted) flat plane cranks can rev higher than standard cranks.

We should all switch to the flat plane crank

That would be interesting. We would all sound like F1 cars racing around, lol! We'd go flying by someone and their faces would look like this: :jawdrop: And our faces would look like this: :mrgreen: :cool:

Wonder if the HP would be significantly higher with a flat plane crank in our motors?

[LGAFF]

Ferrari put a flat plane in the 430

the 4.3L flat-plane-crankshaft dded 20 hp and 4 lb-ft of peak output, but fattens the torque on either side of the peak by a bunch more, making the overall performance feel like much more than a four-percent improvement.

-Motor Trend

[USAFPILOT]

are there any reliability concerns with a flat plane crank?

[LGAFF]

Would destroy your wallet, I believe it was $22K to have these made.

[tpepmeie]

Wonder if the HP would be significantly higher with a flat plane crank in our motors?

http://www.zr1.net/forum/showpost.php?p=86985&postcount=10

I did some testing with Lotus' simulation software on this very topic. There is a gain, 20 hp wouldn't be out of the question.

Todd

[tpepmeie]

Would destroy your wallet, I believe it was $22K to have these made.

How many do you want? Here are the prices as of 2006, from 1 of 2 suppliers to the race team. They were kind enough to send me Lotus factory blueprints to check out before I ordered. I decided against it, due to the vibration and shorter stroke. Today's exchange rate is about 1.5.

1 off @ ?2,800.00 (approx. $4,820.00)
5 off @ ?2,550.00 (approx. $4,385.00)
10 off @ ?2,300.00 (approx. $3,955.00)

Delivery would be 10-12 weeks from confirmation of order.

[Aurora40]

When the Aurora V8 still competed in IRL, and the 180-degree crank debuted, it was good for 20-30hp on ~650hp engines that turned ~10,500rpm. Some lower budget teams stayed with the 90-degree setup.

I bet it would sound wicked on an LT5, but how would you deal with the spark and injector change? Could you just move the wiring? You'd also need new cams, I would think.

Also, on the vids. Are you sure that's an LT5? I think the Elise GT1 had a few diff engine setups? It doesn't sound like I'd expect, it sounds smaller.

[XfireZ51]

Ferrari put a flat plane in the 430

the 4.3L flat-plane-crankshaft dded 20 hp and 4 lb-ft of peak output, but fattens the torque on either side of the peak by a bunch more, making the overall performance feel like much more than a four-percent improvement.

-Motor Trend

Sure sounds like a Ferrari

[Paul Workman]

Very interesting, thanks for posting that LGAFF! Learned something new today! :mrgreen:

A flat plane crank LT5 definitely has a unique sound. A real screamer! What is the rev limit on it? I would think it would have to be as high as maybe 10K since (from the info you posted) flat plane cranks can rev higher than standard cranks.



That would be interesting. We would all sound like F1 cars racing around, lol! We'd go flying by someone and their faces would look like this: :jawdrop: And our faces would look like this: :mrgreen: :cool:

Wonder if the HP would be significantly higher with a flat plane crank in our motors?

Energy required to increase the speed of rotational mass increases at the square of the rate of change in rotational velocity... I guess we intuitively understand that when switching to the aluminum FW. Less rotating mass in the crank would mean even less energy absorbed by the rotating mass.

So, it seems clear that once the clutch is fully engaged, more energy would be transferred to the wheels instead of the rotating mass - a good thing. However, it would mean less energy would be available at the starting line when the clutch is dumped. But, it is intriguing to think about!

Interesting topic. Thanks Lee.

P.

[jonszr1]

they did a test at carcraft about 4 yrs ago i think. they started with a stk flywheel up ugraded clutch and pressure plate . and if i remeber right the alluminum flywheel was about 2.5 tenths faster and 1.2 miles an hr faster that the stk fly wheel . i think it was a 69 nova so the stk flywheel could be lighter than our the 40+ lb flywheels stk . it can be a little tricky to launch the car . the key is a good burn out and leave about as i do right or wrong @4700 rpm . but i alos have a new set of nittos which bite way better then the micky drag radial (street version ) . if i did that with the stk flywheel id burn till i let off.but still either petes style which is a 19 lb flywheel, or the alluminum is the only way to go . jmho . car feels tons faster :mrgreen:

[todesengel]

SInce most engines with a flat plane crank have balancing shafts incorporated, woudl we run into the balancing problems? I mean I could see that it would be less hassle for a "race" engine that is torn down all the time, but for a "street" car, it could become a bit of a mess. Opinions?

[phrogs]

I have a flat plane crank in my ferrari its an old *** 308.


Ferrari put a flat plane in the 430

the 4.3L flat-plane-crankshaft dded 20 hp and 4 lb-ft of peak output, but fattens the torque on either side of the peak by a bunch more, making the overall performance feel like much more than a four-percent improvement.

-Motor Trend