3RD GEN POWER OPTION THREAD

[doug1548534725]

Well, going from the light side to the light side is the same difference as going from the heavy side to the heavy side. I guess my point is that most people are assuming that they'll want to be heavy when they're currently running light, and the table hasn't even really been released yet.

[doug1548534725]

Another thing that could be opened up rule-wise is the nebulous "port and polish" that could squeeze a few more hp out of existing parts. There's also ram-air intake which is essentially free on some platforms, but if there's any real gains to be had there, we'd need to mandate running the big fan while dynoing.

 

I can definitely say that I want to continue running my carb car, and hopefully none of the upgrades will be EFI-only.

[jeffburch]

Mmm, open up the rules with unverifiable port/polish AND mandate a big fan on dyno pulls?

 

What platform do you run in CMC Doug?

 

thx,

jb

[rsmith350]

This is something that I found while looking for 305 info. Not an exact solution, but some food for thought:

 

http://popularhotrodding.automotive.com/44779/0667-phrs-305-chevy-engine-blocks/index.html

 

Nice dyno graph...has a fairly flat torque curve too. I could have saved myself ALOT of money by just throwing in an LT1 ( I have three at my shop in great condition) I have just spent over $1500 re-building my 305. What happened to "cost containment" and the "spirit of the series"? Count the guys that are running 5.0's currently and multiply that by the cost of a new LT1 and see if the directors like that number It can be done with a 305. I think people need to quit being so negative and help come up with a solution. This is were we're going...do you want in or not?

[doug1548534725]

I run a third-gen carb 305 with a "spec" engine package. What's to verify if it's allowed? Either it's allowed and they did it, or it's allowed and they didn't do it.

 

I've yet to see a dyno that doesn't have a fan, and it costs nothing extra to use. I changed my mind on that though, since I just remembered that people dyno their own car without others watching. Just trying to come up with different options.

[ls168camaro]

I still think there should end up being a crate small block as a spec engine allowed in any platform. I think the GM crate 350 for under 2k would be perfect.

[Glenn]

I still think there should end up being a crate small block as a spec engine allowed in any platform. I think the GM crate 350 for under 2k would be perfect.

 

i sent the directors this P/N if they want to spec a 350.

http://www.jegs.com/i/GM+Performance/809/12499529/10002/-1

[camaro_1le]

I still think there should end up being a crate small block as a spec engine allowed in any platform. I think the GM crate 350 for under 2k would be perfect.

 

i sent the directors this P/N if they want to spec a 350.

http://www.jegs.com/i/GM+Performance/809/12499529/10002/-1

 

Now with this option can we run the TPI set and the T5? I have not had time to call Jegs or Summit. Actually, I sent the directors the Summit entry for this motor when the discussions first arose a few months back.

 

So we can pretty much eliminate the LT1 option.

 

No one has shot any holes into being allowed to run a 350 one piece rear seal short block with my 081 heads and LB9 cam....

[Al F.]

Guys you gotta try to compare apples to apples. Dont compare the cost of a junkyard engine sitting on the pavement to the cost of a rebuilt 305 installed in your car. Obviously the simplest thing to do is upgrade the 305 with bolt on goodies, and we're aiming to step our way up some bolt ons to see where we land. Allowing a 350 path makes a lot of sense to me as well. There's no way we're going to leave the carbs behind either.

 

I think that GM crate engine would be a bit shy of the numbers once you add drivetrain losses, but there are plenty out there. Specifically, there's an edelbrock crate engine rated at 315/372 (so est. 260/310) that is essentially our spec carb package punched to 350cid with a set of heads.

 

I would think worst case scenario for the TPI cars would be a set of vortec heads, intake baseplate, a little more cam and shorties.

[powerslide91]

Interesting to hear, and thanks for giving a peak at where you think things are currently pointing. I've been under water enough with other things (work) that I have not spent much time really thinking and researching, although off the top of my head I really like the idea of allowing a 350 option in the 3g cars. I also really like the shorties idea. The manifolds cook everything under the hood on my car, even if they don't add power I'd still be in favor of being allowed to use them if desired.

 

Can I ask who the test mules are for the tweaked 305 and the swapped 350 route?

 

Jeff

[Al F.]

Jeff, its a team effort. Here in Tx Ross is going to be our test mule with a 305. Its in the shop now, probably looking at 2months before we can dyno. First set of numbers will be current tpi w/shorties and 1.6 rockers. I have emails from a couple of others in other regions but I dont have the names off the top of my head (sorry guys!)

 

By the way, anyone 3G driver named Jeff is either going to have to stay at current power or add on an NHRA spec parachute (deployed of course).

[CMC#11]

 

By the way, anyone 3G driver named Jeff is either going to have to stay at current power or add on an NHRA spec parachute (deployed of course).

 

Great idea!!

[cmc38camaro]

Thanks for starting this thread it should help us talk through some of the options. I would have jumped in sooner, but I was away from a computer, I make a living working on the things and when I take a few days off they are the last thing on my mind.

 

There are many constraints we need to work within. First we must fit within the bounds of CMC. One of the keys here is CMC is a near stock class. While some amount of updating and backdating is allowed, it is contained to major platform breakpoints. This defining characteristic of CMC rules out LT1 or LSI swaps. AI is the class for that.

 

The next biggest constraint we have is a bunch of existing cars that we want to bring forward at reasonable costs. This requires us to come up with 305 TPI and Carb packages. Additionally I will be pushing my fellow directors to allow 350 TPI and carb packages. The 350’s are not a done deal, so stay tuned, I will have more info later in the week. Keeping costs controlled in my mind means first looking at simple bolts on to find the needed power. Things like 1.6:1 rockers and headers come to mind.

 

The 305 carb engines make a lot more than 260 HP in A-Sedan trim. Obviously their rules are more open than ours, but I throw it out there just to show these engines are capable of making the numbers with GM heads. What we are trying as a first shot at making the needed power is a performer RPM, 1.6:1 rockers and headers. My DynoSim software suggests this will make 27 more hp and 51 more ft-lbs at the rear wheels. Obviously we can’t take simulations results as fact so this very combination is being built and will be dyno tested. If it falls short I would suggest we look at a different cam, even with 1.6 rockers the 2102 spec cam is a small dual pattern cam. I will model some other cams when I get some time.

 

Modeling the 305 TPI engine with headers and 1.6: rockers shows a gain of 30hp and 35ft-lbs at the rear wheels. The torque increase is disturbing, simply said the TPI motors will bump into the torque limit long before hitting the torque limit. I think some cam research is in order and again I’ll get around to that soon. I talked to TPiS about our plans, about this engine combination and about many things TPI related. First, they agreed that headers and rockers were a good first shot. They said that our power levels the throttle body, plenum and runners presented no significant problem. The heads are the major impediment to making power and the intake base is also problematic. Stock computer programming will work fine with these basic modifications. Computer tuning is another topic we discussed and it would certainly help in our quest for power. It does however open a major can of worm that I would like to avoid.

 

I will hold back my thoughts on 350s until I can confirm one way or the other if they will be allowed.

 

A few notes on heads. First we should try make the heads that came with our 3rd gens work. They are not great heads by any streak of the imagination, but they are the stock parts and we are a near stock class. 305 and 350 heads are different even though they bolt up. The 305 heads typically have 58cc chambers while 350 heads typically are 64cc or 76cc. Over time there been other variation, but our f-bodies came with 58and 64cc respectively. One long standing trick has been to put 305 heads on a 350. This bumps the compression by about .85:1 if everything else remains constant. The compression ratio debate has raged on other threads and I believe we will end up at a blanket compression ration of 9.6:1 for the 3rd gen cars. This needs to be agreed to by the other directors so don’t take this as fact. Back to the 305 head on a 350, bolting a 081 305 head on a L98 350 will yield a compression ratio in the 10.15:1 range and I expect this will be outside the rules.

 

Conversely, bolting a 350 head on a 305 gives up compression. Then there is the mechanical interface angle to look at, the cylinder bore of a 305 is small in comparison to a 350 and head and piston combinations may not work.

 

Vortec heads are a popular idea. The vortec 305 and 350 heads are different animals with the 350 heads flowing great while on the other hand the 305 variant are swirl port heads and are not highly thought of. I would love to see actual flow data on the 305 vortec heads if anyone has it. The vortec heads have a unique intake bolt pattern and require specific intake manifolds. Like someone said, a TPI vortec base is available but is spendy. Again, let try to make the stock castings work before we go this more expensive route.

 

More soon.

 

Mike

[doug1548534725]

27 more hp and 51 ft/lbs?

 

Is that the Performer RPM Intake, Cam, or both?

[cozog1548534733]

First we must fit within the bounds of CMC. One of the keys here is CMC is a near stock class. While some amount of updating and backdating is allowed, it is contained to major platform breakpoints. This defining characteristic of CMC rules out LT1 or LSI swaps. AI is the class for that.

...

Additionally I will be pushing my fellow directors to allow 350 TPI and carb packages. The 350’s are not a done deal, so stay tuned, I will have more info later in the week.

 

Don't those two statements contradict each other ("stock class rules out LT1" and "I'll push for 350")? Even if you keep the idea of a "stock" class, you're still modifying the 305 to perform far beyond what ever was "stock".

 

Also, The LT1 setups have already been tested and proven on the track, right? So instead of spending the next 3-6 months trying to figure out what the best combo of 305 bolt ons will get 260rwhp, why not just allow the use of LT1 that everyone knows the HP of?

 

If the 3Gs ran LT1s and the majority of 4Gs ran LT1s, wouldn't you have much greater parity amongst the cars? Then everyone could concentrate on DRIVING.

 

And Mustangs could do the same. The 2V cars could get a couple mods so they can keep up with the FBody HP. Or maybe drop the max HP a bit to help them match.

 

Then you have a race series that is just about spec. Fbody vs. Mustang, 350 vs. 281, 17" wheels, dual piston brakes, 275 tires.

 

THIS WOULD BE VERY ENTICING TO A newB LOOKING TO GET INTO "CHEAP" RACING.

 

That's my $0.02.....

[cmc38camaro]

Mike Plum wrote:

First we must fit within the bounds of CMC. One of the keys here is CMC is a near stock class. While some amount of updating and backdating is allowed, it is contained to major platform breakpoints. This defining characteristic of CMC rules out LT1 or LSI swaps. AI is the class for that.

 

...

Mike Plum wrote:

Additionally I will be pushing my fellow directors to allow 350 TPI and carb packages. The 350’s are not a done deal, so stay tuned, I will have more info later in the week.

 

Cozog wrote:

Don't those two statements contradict each other ("stock class rules out LT1" and "I'll push for 350")? Even if you keep the idea of a "stock" class, you're still modifying the 305 to perform far beyond what ever was "stock".

 

No The two statement do not conflict with each other. By 350 I was referring to the L98 350 that was available in the 3rd gen cars. The L98 has not been allowed historically to help keep the field level, we are now switching fields and the L98 is not too far off target.

 

Mike

[cmc38camaro]

Is that the Performer RPM Intake, Cam, or both?

 

The Performer RPM intake, the Performer cam with 1.6 rockers. The rockers bump the duration by about 4 degrees at .05" and increase lift to .448"/.471"

[jeffburch]

Rockers.

Just roller tip or full roller?

 

thx

jb

[cmc38camaro]

JB, the modelling isn't detailed enough to tell the difference between stamped, roller tip or full roller.

 

Stamped are cheap, cheap cheap. Self Aligning full rollers aren't. Do self aligning roller tips exist?

 

Mike

[comeback kid]

Mike Plum wrote:

Additionally I will be pushing my fellow directors to allow 350 TPI and carb packages. The 350’s are not a done deal, so stay tuned, I will have more info later in the week.

 

A carbed 1990's LT1 would be interesting, and less hassle to swap for a car that is all ready carbed.

[camaro_1le]

One long standing trick has been to put 305 heads on a 350. This bumps the compression by about .85:1 if everything else remains constant. The compression ratio debate has raged on other threads and I believe we will end up at a blanket compression ration of 9.6:1 for the 3rd gen cars. This needs to be agreed to by the other directors so don’t take this as fact. Back to the 305 head on a 350, bolting a 081 305 head on a L98 350 will yield a compression ratio in the 10.15:1 range and I expect this will be outside the rules. Mike

 

I agree that the L98 would be a valid option. But which L98? In 1987 and 1991 their compression was rated at 10:1 which puts it over the limit. Given enough time, probably can find a decent one though.

[Dave Schotz]

From the TPI family:

 

At first pass... I like 1.6 Full Roller Rockers, and Headers.

 

I would guess that get's most 'average joes' to 245 RWHP... to get the remaining 15 HP... I think Intake upper & lower would be necessary.

 

I think messing with 305 heads on 350's etc... is not a good idea.

 

If we are going to allow 350's... it can only be whatever GM specs were for the L98 from '87-'92. From what I can find... '87-'89 had 9.3:1 compression... and '90-'92 had 9.7:1 compression based on a piston change.

 

If we're considering Table 3... being the new CMC level 260RWHP / 310 RWTQ... the Stock L98 Probably hits this just about dead on without the use of bolt-ons... But I haven't dynod one close to stock.

 

Carb Family:

I am of no help. I have no experience with them.

[jeffburch]

JB, the modelling isn't detailed enough to tell the difference between stamped, roller tip or full roller.

Stamped are cheap, cheap cheap. Self Aligning full rollers aren't. Do self aligning roller tips exist?

Mike

I realize that Mike on the modeling. I wanna know where you guys are looking. Cheap crap or decent crap.

 

Think so, Summit has many

http://store.summitracing.com/partdetail.asp?part=SUM%2DG6936%2D16&autoview=sku

 

jb

[jeffburch]

If we're considering Table 3... being the new CMC level 260RWHP / 310 RWTQ... the Stock L98 Probably hits this just about dead on without the use of bolt-ons... But I haven't dynod one close to stock.

 

Per TGO, the L98 on it's best day did 245/345 SAE.

 

The announcement thread (by TG) said 300 ft. lb. tq. as the number for 2010

I hope he ment 310.

 

jb

[King Matt1548534716]

Yes, you can get self-aligning roller rockers for the late-model heads. They are comparable priced with any other option, or at least they were 5 years ago which was the last time I had a set. Those stamped rockers with the roller tips are crap and a waste of money. Most of the friction is on the fulcrum, not the tip. If we are going to allow the option of changing rocker ratio it should be with roller rockers, especially since the Fords 5.0s are allowed to use the Cobra rockers.