Road racing and Roll racing

out of low speed corners and UP TO SPEED. 5,6, 8 corners every 2 - 3 miles every 2 min for 30-40 min at at time.

Getting out of a low speed corner is the key to fast lap times, not top speed.

 

If the cubes were similar, the longer stroke would win the TQ contest. 418 vs 441, the extra cubes win.

 

Here is some basic info I have 50% of getting right...Bore size equal, a longer stroke will create more torque, more friction (piston travel), increased rotational mass weight, can be used with a wide ratio transmission etc...

A good LS example is the old Lingenfelter LS1 383.

A shorter stroke to bore ratio is what racing engines have, less friction (less piston travel), lighter rotational mass, less torque down low, and will need narrow gearing to be in it's sweet spot at a higher rpm since breathing is key.

An engine is like a orchestra, every instrument (in this case moving parts) must complement each other.

So it all comes down to... what music do you like?

 

You generally do not ever lock a converter on the dyno because of the high possibility of burning it up. Triple discs can probably handle it, but anything else is just really asking for trouble. I don't personally know anyone who has ever dynod a locked converter. I know it has happened, but no converter company would recommend it.

When I pull out my 3200 yank for a 3600 circle D I'll probably try a run locked to see what the difference is on the pull...and see if holds up alright

I've never done any road racing where I'm taking a corner in 1st gear under 3.5k rpms. Have you?

Low speed corners do not equal low rpm corners.

And how does roll racing prove that you need low rpm power? The entire point of roll racing is to be at speed to not break traction. You don't start roll racing in 4th gear at 40mph.

Low RPM power is 100% useless for any type of driving other than heavy traffic driving.

I welcome anyone to prove me wrong.

 

We have several tracks here in the south east 2nd gear under 2,500 rpms Going to 1st is usless unless you have a racing trans


and my little LS6 with 400 some lbs ft of torque at 3000 rpms can take the LS7s up to red line 3rd gear, then I am toasted

Also tend to corner faster then most cars with bigger more HP motors too.

 

Shawn... that's the way they do it on the a4 trans, it stops the trans from down shifting and is a true 1to1don't know what the conversion would be unlocked to locked, or they would just correct it i guess

 

You're right...I forgot you had the A4

It was the same deal in the Fbodies.

 

I'll take your word for it, but I just can't imagine needing to be under 2500 rpms on a track in 2nd.

What mph is that?

 

I am curious about this thread because I am having an engine built right now and I wonder what it will make for hp & torque. With any luck I will be installing it in two weeks.


416 LS3 stroker 416 LS3 w/Callies forged rotating assy, ARP bolts, XHP Cam, LS7 lifters, MLS head gaskets, Hardened pushrods, LS Oil pump, CNC LS3 performance heads w/dual .650lift springs, Ported oil pump, Nitrous rings, 11 compression. (235 / 259 @50 625 lift 113sep )

 

Just curious what hit the stroker makes to your mpg. I am heads/cam/intake on my LS2 and getting 25 mpg highway with 4.10's. My tune is crap and running rich so I think I should be 26-27. For the guys that went stroker, what did your mpg drop to?

 

I get 22-23 mpg in my mostly honest daily drive with 4.10's so I think you are doing well.

 

Why is that? 2500 rpm in 2nd gear yields the same mph as ~ 3700 rpm in 1st. That would seem to give a fairly wide range to use in 1st. Is the course layout best attacked by staying in 2nd to avoid quick upshifts and then downshifts?

 

At low speeds in first gear, it's probably a handful to control. 2nd gear, at reduced rpm with a high torque motor, is probably less work load on the pilot. He can worry more about hooking the rear bumper of the guy that's in front and placing him politely in the wall

 

That is also the argument for not needing that much low end power. you make less HP at 2500 than at 3700 so why build a motor to add more power down there if you can not control it or use it? It seems like lots of TQ at low rpm leads to the tires breaking loose.

I don't have the road course expertise, so I'm just looking for the insight on this.

 

You should really get a custom spec'd cam for a stroker by someone who knows what they are doing. Increasing the stroke is going to want to peak earlier in the RPM range which might not gain you much power over the stock cubes if running a similar cam, but will gain average and peak torque. Extending the torque curve higher into the RPMs is how big power is made.

 

Nice ...back on topic

I agree 100% with your comments, however I must say this. I've had 4 cams spec'd, the Intake duration ranges from 234 to 243, the exhaust from 238 to 247, overlap from 9 to 17*, lift all .600 to .650. This by the known cam profilers. Then you talk to various shops & look out.

So the confusing part is of course how to choose, do you have experience with strokers & cams & would comment on the original post?

 

Any other stroker builds? I'm very curious how substantial the gains would be if I swapped out my ported 243s for an AFR or Trick Flow head. Anyone have any experience with before and after gains, whether it is stock CI or not?

 

Correct. Corners are about 42-45 mph. VIR Left hook and Oak Tree, Road Atlanta T7

1st gear in the STOCK manual transmission are almost useless on a road course, the ZR1 and GM Motosports gear box is a different issue

ppl tend to forget that each sift is 1/4 sec, so a downshift and upshift is 1/2 sec. may times the corners come too quick that short shifting keeps the car stable vs attempting to shift to a lower gear and upsetting the rear end in corner.

For your enjoyment

http://vimeo.com/20208440

Specs
C5Z06 stock motor ~380 rwhp ZR1 trans with 3.90 gear Wilwood 6 pots Full aero

and

http://www.youtube.com/watch?v=MgThLg-_sVc

Specs
Specs: C6Z 570-ish wheel hp, LS7 with LG G7X5 camshaft, headers, light clutch and RAFT custom tune, RAFT transverse leaf suspension, StopTech brakes, NO AERO (yet), Hoosier A6's. Yes still has full interior , NAV, radio, AC all the bells and whistles. Car is 3080 without driver. It is about to get full blown aero which will probably be 2 sec reduction @ VIR. It was stooopid hot that day and should have ran 55's but we missed the "money round". Cooler air and the car should go in the 54's ,faster with aero This car IS a street car.....

 

Im just posting up two results for data points.

DTE/Phil had posted a thread on a 416 stroker with 100% box stock LS3 heads which sparked an observation in my path. It used a 230/242 cam and made 500/500 to the wheels.

It was this build that made me try a 230/234 and it made the same power on my car.

I tried a 230/242 with its 4 additional degrees overlap and in a stroker it drove ok but the 4 degree overlap 4 degree split drove better with the same power. I also tried a 230/236 both with 6 XFI lobes and it made slightly less TQ. Bigger cams do run better with more displacement and more compression.

Just sharing.

On a personal note. If I built a stroker and didnt at least match the power of a cammed stock stroke LS3, I'd be pissed. Seeing huge cam strokers making 480rwhp and 480 or less TQ shows me its too much cam and ported LS3 heads are a waste of money. 550rwhp is trick flow head on a 416 stroker or bigger. They are worth the extra $1k.

In the end there seemed to be a sweet spot on cams, past which bigger diudnt make any serious power gains.

Those displacement generated cams are:

5.7L = 224 cam---Cartek's 10.53 1/4 mile car
6.0L = 228 cam---455rwhp stock heads w/FAST
6.2L = 230 cam (A 227 LSL has way more open time) 500/455 rw
6.6/403 = 234 cam 522/488rw--customer ETP 215's
416 stroker 230 to 234 500/500 for the 230 cam
427 (Phil Jimenez) with trick flow 235's was 236/242 114 LSA at 578rwtq

I have never seen stupid sized splits do any better unless more lope is 'better. A 227/239 is still 500/455 or so on an LS3. A 234/254 cam on a Z06 didnt bette Phil Jimenez' 427.

Phil from DTE posted his results in a thread in this section if you want to find it. It was to share a stock LS3 head result with a small cam.

 

The power is made in the heads. Better heads make better power.
The cam controls the timing of it all. You want your power to be in a certain rpms range you cam in accordingly.
Its all relative...

Heads are not just about flow numbers but better generally more flow makes more power as long as things are equal...( valve-train is set up correctly) But more flow is relative to rpms and the need for air up top...

A proper combination is what you are after. Cubic inches and head characteristics and the cam all work together in harmony... its not something that you just piece together. This is why some 416's make 500 rwhp and some make 550.. HKE just fixed an engine for someone and all he did was set up the valve-train with the proper components and cam and picked up 70 hp... the cam lobes and springs and cam were a poor choice and done by a professional shop...