Just thought I'd throw it out to you guys to see if I should do anything different.... This all started b/c I was flogging the crap out of the ole girl.. I had rebuilt it two years ago and about 10k miles ago.. I ended up burning a couple pistons.. All my fault no parts failures or improper parts selection.. I ran about 10 1/4 mile passes back to back and ended up doing the damage... Oh well.. Here is what I'm thinking of right now...

327 small journal block
350 SCAT crank with the mains machined down
L79 Intake
2.5" Ramshorns exhaust manifolds
AFR 180 68cc heads
Comp Cams XE274H
Comp Cams 1.52 forged roller tip rockers
JE Pistons' SRP 4.040 Pistons CR of around 9.9
Eagle ESP H beam rods

So what does the forum think I should keep or change.. Thanks as always.. Dave..

 

What length will your new con rods be? Is the crank a forged unit?
(I wonder about the longer stroke of the 350crank and how much will
you be taking off the main journals)

I would lean toward ceramic coated headers.

Have you thought about the Lunati Voodoo series cams?

I,m sure your ignition system is fine (I was there when Lars helped you
tune your vehicle)

Outside of the crank, I dont think your choice of parts are bad at all.

Will be watching for printed ET slips once done.

Drive fast....Take risks

 

Why would 10 1/4 mile runs wreck the engine. I have done 17 back to back and many times done 10 or more with no trouble. Was something wrong with the carb settings to lean the mixture to much.

Your selection of parts seems to be pretty good. Should wake it up some.

 

My LT-1 has been running 12 second 1/4 miles for over 14K miles with autocross useage in between the drag strip use. My motor still has great oil consumption. I had my machine work done at a shop that uses Sunnen honing oil at about $1000 a barrel and they change the oil for new oil following Sunnen's recommendations (many shops buy BrandX or recycled honing oil for their units, they are STUPID!) They also take extra time to clean the cylinder bores properly with ATF after honing them and not just do a 2nd hot tank of the block calling that good enough like most shops do. Funny thing about my machine shop, their motors are noticeably faster than most of the competitions at Altamont Racetrack and Stockton 99 Speedway but, when torn down, they are found to be legal. There are quality shops and the rest, the good guys usually don't charge much more than the other guys, you should go to the races and seewhich shop is getting the job done at the local circle track NOT! at the drag strip, or car show.

 

It seem that I had some detonation. I had recently had an AF meter on it and I was running right at 13:1. My ignition at last check was 16 initial and 36 total at 3000. I even went as far to have the NC Ag department check the gas. 92.6 Octane. I'm still not exactly sure what happened as I didn't think I was beating on it that hard. I made 10 back to back runs in that I ran her up from 0-100 then stopped turned around and did it again. 10 times. I have to only guess that my cylinder temps were extremely high just due to the nature of the beast. Dave..

 

I would say that the detonation is probably what killed it. You should be able to do as many back to back runs as you want to without engine damage. Any race car is continually doing this for hours. Either a fuel mixture or ignition problem was there. I might be building a stroker motor myself this winter. Anytime you can get more cubic inches into your motor you should make more power. Your new combo looks to be good.

 

The crank is a 350 cast steel crank, SCAT claims that it's good up to 600 hp and 7k. I don't see the need for the forged if the manufacture doesn't feel the need to sell it to me. The mains are turned down to the small journal bearing size.

It seems that the biggest problem with my setup is the AFR heads in that they are 68cc chambers and most pistons are setup for 64cc heads. The AFR heads require one of the following flat top pistons or the heads machined...

Well I haven't found a problem in the ignition map or the carb so with a static of 9.75 CR from before with the cast heads I'm unsure as to what could have caused the detonation.

It looks like my CR will be about the same this time as it's computing up to 9.8 static. The desktop dyno puts it no where close to where I would like to be as for HP.. It looks like making a true 3 hp and 426 torque..
RPM Torque HP CFM VE%
2250 415 178 231 92
2750 420 219 283 93
3000 421 241 308 93
3250 426* 263 334 94
3500 423 282 360 93
3750 419 299 386 93
4000 414 315 411 92
4250 405 328 437 90
4500 395 338 463 87
4750 384 348 489 85
5000 366 349* 514 81
5250 342 342 540 75
5500 314 329 560 68

How are guys making big hp on the street on pump gas. I thought I was doing everything right but guess not... Dave..

 

Try a quench hieght of .035"-.050" to help sqwish the fuel mix and remove pockets of bad fuel mix. That's distance between piston top and flat of cyl hd covering bore - includes hd gasket compressed height.
If ur burning pistons ur either detonating or pre-ignition - my quess is pre-ignition from too much advance.
Get an MSD knock sensor and dial it in (adv - full curve) as i can tell from ur posts u would put one on and use it right. Now i haven't used a knock sensor myself but have 1 on the self waiting on my to do next list. But nearly every new EFI 'puter has and uses 1 so i expect they work.

Yes tighter chambers produce better combustion but can't put a number on power gain. Hey who needs AFR heads on a street fighter? Tight chamber Edelbrock or Trick Flow heads are fine heads too. Anb 10.2c.r. will work on pump gas and make more pwr than 9.7c.r. (aluminum heads of course). With good quench and a large overlap cam then 10.5c.r. should work to for more power yet (again alum hd).
But for big cams and higher rpm's u gonna need headers to make pwr dude.
BTW hypereutechtic pistons seal better than forged pieces and usually lighter too - half price also.

Well if ur building ur own mtrs yourself then go with a solid cam - ain't nothing made more reliable than a solid lifter. Again make more pwr but remember solid duration not same as hyd (full or .050") - u need to research this to upgrade rather than downgrade to smaller cam.

Ok i'll shut up now but hope this is something that will help u more than confuse u. :o
cardo0

 

Any particular reason you want to turn down the crank? 327 and 350 have same 4.00" bore. So you are going to end up with a 350, why not leave the extra material on the crank and build a 350 using a 350 block? Just asking a question to see if I'm missing something.

ltlevil

 

I just wanted a correct look for my car, something along the lines of the FAST class. I'm looking at http://www.castheads.com/corvette_systems.php
to help with my exhaust flow dumping into true 2.5" side pipes. I'm not a NCRS ****, just what I like because my car is far from correct. I guess I could just throw a 502 in there if it was that easy. I went with the 350 crank to accomplish the same thing as having a 350 but with the 327 look.

I know silly, right?

 

Dave -

First, a disclaimer: One could fill books with what I don't know about engine component selection and compatibility. Keeping that in mind, here goes .....

1. Ten passes down the strip should not have damaged your engine. It may have accelerated a problem already present. When you build your new engine, it might be a good idea to have it tuned on a dyno to ensure the fuel-air ratio and timing are where they need to be for power and engine longevity.

2. I think a lot of folks buy too much cam for the street and then are unhappy with driveability at typical street rpms. However, with your cam, I'm surprised the torque peak is so low. I would guess low end driveability would be great, but at the expense of peak HP. If more peak HP is what you are looking for, there might be a better cam out there for you that has an equally flat torque curve but a higher peak torque, which will likely produce a higher peak HP. For most folks who are interested in good throttle response, driveability, and seat-of-the-pants push-you-back-in-the-seat performance at street speeds (but not peak HP shown on the dyno sheet), the cam you selected would probably meet their needs.

3. If you have to buy a crank anyway, why not buy one with a longer stroke? Displacement = HP. All other factors being equal, a 383 will produce 9% more power than a 350.

Good luck with the project, and keep posting progress reports. Most of us will have an engine rebuild at some point in our futures, and we can learn from your experience.

Mike

 

Those Brzezinski exhaust manifolds are intended for restricted hobby/street-stock circle track racing classes where headers are not permitted ... they're "cheater" manifolds ... they're nice but ... a $120 set of tube headers will outperform them everytime. But if you want stealth power ... why not use your 327 block, a set of Brz disguised World sportsman2 heads, a 383 rotating assembly, a Brz disguised-but-hogged-out iron intake and Brz cast exhaust ... done right, you'd probably have $10K in & get 450-475hp out ... & virtually nobody'd be able to tell until it was torn down.

Or just build an AFR head 383 w/ tube headers ... same power for 1/2 $.

 

Not silly at all, I actually wondered about that after I typed my question. Seems there is more and more interest in the FAST class these days, good to see something like this for those of us who don't want to or are unable to spend the bucks for an 8 sec street car and compete in some of those other classes. Good Luck hope everything works out for you.

ltlevil

 

Everyone makes good points keep em coming it's what I need. I'm still undecided as what all I want. That's why I've only bought the parts that will work for what ever way I go.

If I were to go to the 383 crank wouldn't machining the mains down to small journal size reduce the strength of the crank greatly as it will be come extremely small?

The SCAT cast steel crank is the one that I bought and had in the motor from the last build. I'm definately thinking about going ahead and upgrading to a Forged unit. SCAT claims it's not neccessary but hey it'll be bullet proof right.

Jackson yea see I know that I'm going to be spending more money to achieve the same hp as some advertised crate motors. I don't plan on running in the FAST class but I like the idea. And that the car will have a stock looking engine but be a monster on the street..

I may just be crazy and have more money than sense.. Dave.

 

Ttt