Is there a "realitvily" easy way to caculate Exhuast / Intake ratios of cam and head combinations??

I see all these numbers of air flow on heads, then angle of the injectors 15* vs 11*, valve size, then the cam numbers

I have been doing a lot of reading and it makes my head spin.

TIA

 

You might get some well meaning responses that offer suggestions like "this is what I do" or "use this because it works for me" but the fact is there are no magic formulas and no computer programs that can accurately pinpoint this. There are far too many variables to take into account for any formula or computer program to possibly consider in order to generate an accurate answer but you might at least get a generalization which would point you in the right direction. I am in the professional racing business and we have a fully staffed research and development program with many engineers with Masters and phD degrees and it still always comes down to cut and try. Basically we build test mules to see if it likes a change. We test for performance gains first and durability afterwards if we decide to pursue it. We had a promising phD emgineer join us a few years ago who wanted to design cam lobes and cam timing by measuring cylinder pressures, intake manifold and exhaust system pressures in a running engine. This involved installing pressure taps in the heads and manifolds and pretty sophisticated software to measure and analyze real time data and it didn't do much of what we wanted. We still hook it up for a dog and pony show from time to time when dignitaries are scheduled to visit because it looks impressive but otherwise it's pretty useless. There is no substitute for knowledge and experience in just knowing what these things respond to and what they like. Simulation does have it's place, however, but it is just another tool to consider along with all the other tools and not an end unto inself. You can still have some fun with it I suppose; there is even some software out to simulate dyno runs that could be amusing for a while.

Regards, Greg

 

Greg

That is kinda what I thought. Just trying to be an educated consumer when I talk to ppl like yourself.

In short, I do open track days or HPDEs. I do a lot of 50 to 150 mph runs out of corners and down straighs, VIR's Oak tree turn and long back straight, plus VIRs front straight,

What more low end tq then end HP and what to get out of corners ASAP. 2000-6500 rpms
nice flat torque curve.

I have an 03 LS1 motor with 90mmTB, bigger CAI. different MAS, LTs, 3" exhuast and straight pipes , redline bumpped to 6750 and so very good tuning. T1 suppension, Car is very very strong out of corners, but some times I think am at the upper end of the stock range and reliabilty.

I have driven several ZO6s with popular head and cam packages, and I did not feel they were any faster, especially out of corners then my car. May have been the MN12, vs my MN6 tranny which I like much better.

TIA
Tom

 

If you are serious about track performance there are some things worth considering. Sorting the chassis, suspension, tires, wheels and brakes will yield a far greater improvement than working on the engine. This is not to say the engine is not inportant but rather that the car is more important. The engine should be set up to deliver reliable useable power in the ranges you are at WOT. Look at the track map and decide what your realistic RPM ranges are at different points on the track; this will help you decide on a cam. Your first concern should be for reliability. I would address the LS-1 weak points first (perhaps someone with LS-1 experience will advise on this) and maybe look at the oiling system. Road courses are tough on stock oiling systems because the oil always wants to run away from the pickup during hard cornering and braking. I would be tempted to get another engine to modify and store the original stock unit in the corner of the garage.

Regards, Greg

 

Car is almost a full T1 set up

Suppension GM T1
3qt accusump and oil cooler
trans cooler
car cornerweight & balanced

brakes- stock corvette PBR calipers, but wilwood H racing pads, Castrol SRF brake fluid. DRM brake cooling ducts. I have driven many cars with BBKs and am not impressed with their preformance. I need to drive a car with StopTechs or AP-Racing set ups.

I use Hoosier R compounds.

I have taken care of just about every thing BUT THE engine.

Cage goes in next. before the motor

I was getting the impression of a new block and building or having one built. Then storing the stock LS1 as you suggested.

Thanks for the tip on the RPM on different parts of the track. I will go back and look at the data logs and on-board videos.

I have severl 1000s miles on VIR alone this past 3 years. and have many more miles / laps planned. I dont plan on taking the engine lightly and wont jump into it either.

 

What I have found to be immensely useful is two books by David Vizard, one on cylinder heads and one on valve trains. He does a very good job. The books are aimed at the SBC, the principals remain the same.

 

Head & Cam setup will net you more power than you have now probably 75 more HP 60 more lb. ft. You won't lose on the bottom either. If Katech can't build you a motor who can?

 

Since you have an non-Z06, and you want low end torque, you may want to consider gears instead of cam & heads? Maybe a set of 3:90's would give you what you want and you can leave your motor stock? Just a though? I would hesitate to put gears on a Z06 tranny, just because the gearing is already aggressive, but this may be the solution for you. I know with gears you gain lots of torque and no HP. It sounds like your looking for torque.

Instead of going crazy thinking about all the options (custom and off the shelf), I went with a proven set up from LG (recommended by Lou) that is pretty popular (G5X3). I know you and I have been discussing this back and forth for a while, but instead of trying to put something together myself, I went with a proven recommended solution. Is it absolutely perfect? I'm sure it's not, but at least I KNOW it works well and has been on the market for a while, and is backed by LG. After going for a ride in a G5X3 car, I was sold.

Good luck with your choice, but sometimes we tend to overthink things and were better off just going with a proven set up.

 

Yes proven set ups may be best.

I have driven two ZO6s with LG G5X3 cams, one with AFR heads and one without. I was not impressed at all. My car still had more getting and gone out of corners then these set ups. My top end I wasent even close, however, no straights where long enough to use it. I also suppect that I drive my car harder as I know my car and I do not drive other ppls cars like I drive mine. Then when I followed these cars, I was on their tail though corners and they could only pull away above 125 mph, but then I would catch them in the braking zones and in the corners again. If I do say so I am a very smooth driver, not the fastest by any means, but very very smooth.
Could also be the LG cams need 3500+ rpms all the time to really get the power. I may need to learn a different driving style.

I have played with differnt rear end combination charts too. Diven 4.10s and that was a joke, spent more time shifting the driving.
I have not driven 3.90s or 3.73s

I prefer the MN6 over the MN12s. and also played with different gear combination charts.

When I look at the price of cam, heads and all the extras, a Ketech 402 is not far off in price.

So I will just keep driving, reading and learning.

 

You can't drag a gas motor down like a diesel to 2,000 rpm. When I am at Pocono I am in second on Devils Elbow (tight turn 180*). Everyone starts asking me why I gain so much on them. It's because I am using my power. Even with a stock motor you want power you need rpm's. Oak tree would be second for me also on a dry track.

 

VIRs Oak Tree turn is a perfect example. Most corvette shift down to second to get the power out of the corner. or presumbed power and feels much faster. When you go a little faster 55-57 mph vs 50-52 mph though the corner and say in 3rd gear, you wind up having more power and shift to 4th 50 feet before the south course timing tower, vs going though Oak tree in 2nd at 52 mph you dont shift to 4th until after the south course timing tower. about a 60-70 foot difference when shifting to 4th at 105 mph. ( or am I giveing away my secreats at that corner ?? )

Watch the video posted about Viper days over in AutoX and RR. He uses 2nd though Oak tree and does not shift to 4th until the timing tower.

I also understant about not dragin the rpms down to 2,000.. at oak tree I am a 3rd gea, 3500rpms ( 55mph)and use the low end torque to get up to speed.

I will be back at VIR the next two weekends and run some fresh data/ video combinations.

Hmmmm

 

I don't pay that much attention to all the things you have written in my mind but the faster I can get in the gears and redline them the faster I will go. You want to stay in your power band as much as possible and you will shift past peak torque to keep in the HP band for quick recovery in the next gear. If you are saying your lowest speed in the Oak Tree turn is 57 MPH I think your the fastest I have seen there. I'd have to look at my vid's but doubt my lowest speed is 57.

 

That is my problem John I am analysise everthing.

 

I agree with John, to make power you need RPM in any motor. I also agree that the G5x3 didn't really come one until 3400, BUT...I could feel that it still provided as good or better than stock power/torque between 2200-3400k. Below 2k it was a dog...but below 2k, I'm either pulling out of a parking lot or cruising down the highway?!? Also of note, the cam DID NOT buck or surge at 1500.

I also think it depends on the track and purpose of use. I have never done auto-x, but I can see how a cam which provides more low end torque could be beneficial vs a G5X3. I can also see that a lazy driver who doesn't like to shift frequently, would benefit from a closer to stock power curve vs the curve of an X3.

But Pocono, Watkins Glen, Summit Point, and soon to be Thunder, are ALL HP tracks, and I spend 95% of my time above 3500. Even if there was 1 corner (5%) that I might pull out of at lower RPM, I would rather have the upper RPM HP for the rest (95%) of the track. Don't build a motor for 1 corner (oak tree turn). Just deal with it, and learn to take it a new way. I have never driven VIR, but I guarantee you are above 3500k rpm 95% of the time.

I will have my car back on Friday with the G5X3 installed, and will tell you how it feels. You may want somethink like the X2? I am told it comes on 200-300 rpm lower than the X3 but still revs great up to 6500.

As I stated above, you might just be good with a set of 3:90's. This way you keep the motor stock with stock relaibility, but more torque and quicker revs.

The other option is bigger cubes. This will definately give you the torque with the high end HP, but definately at a cost.

 

I'm there to enjoy. People ask me what gear where and when at Pocono and they think I'm them when I can't tell them. I need to go out next session and pay attention to tell them. It just comes automatically. Like you guys at VIR talking corner #'s I'm and I did notice the tree