388 SOLid RoLLeR

Im hearing 11.5 :1 is not a problem for pump gas...

i figure reverse flow cooling helps somewhat. What do you guys think.

gkull

http://cochise.uia.net/pkelley2/Overlap.html

using their little forumula I ended up with 8.38. My motor doesn't ever ping on 91 octane. So I wish that my DCR was a little higher. with a 3.750 stroke having over 245 degrees of intake duration at .050 11.5 static should work.

IMO - build your motor to withstand 8000 rpm. then cam it for max power under 6500 rpm and use a 7000 or a little over rev limiter and your motor will last a long time. I've put nearly 20K miles on mine

69 N.O.X. RATT

Gkull: I have used that same web site and wonder how accurate it is? It seems to me it leaves out some important info, like head flow data. I have to believe the head flow has a lot to do with dynamic compression.

I agree with the build them to with stand a lot, and cam them for the street.

gkull

(69 N.O.X. RATT)

Your right that you have lots of variables. Tuned intake tracks whether it's dual or single plane, TPI, superram or a variation can achive with correct cam timing and rpm over 100% VME or substantially less like 80% cylinder filling. New fastburn type heads and small quench space can skew those figures also.

At least it gives you a starting reference.:)

388 SOLid RoLLeR

LT4 heads/intake. fully ported (305+cfm .550)

The cam we got should make peak power around 66-6800 the comp guy and the shoppe builder said. With the Dfi setup im going to install, and because its a solid roller im hoping to make power up till 7500 hopefully higher... not peak but still generate enough to rev it that high. the heads flow very well, and the bottom end is bulelt proof , i hope... Callies crank, oliver billet rods, Forged srp pistons. etc.. we went with a 5.85 rod length, and the piston is a .060 size which gives 388 . :cool: the valvetrain is top notch too, crower rockers, titanium retainers/shims, dual springs etc...
what do ya guys think?

388 SOLid RoLLeR

the whole deal was he told me 11.5 compression and i was like :eek:

this guy builds vipers that continue to kill LPE and TNT vipers so he knows what hes doing. he also builds some BUSCH series motors and did nascar heads before....

i trust him, but i was just kinda freaked when i heard 11.5 !!! i never put anything below 94 octane (sunoco) but i wanted it to run just as good on 91. i just dont liek the idea of putting in higher octance gas and running faster. I drive the car alot, and dont want to be stuck anywhere with bad gas and have to risk my motor. hopefully a trip to cali will be in the works next year... :cheers:

racerns

I am running 11.5:1 on my 396 LT-4. I have had no problems so far with running 93-92 Octane gas. (no knock counts detected) I think your only problem might be reduced performance when running 90 or 91 but not damage if you have your knock circut hooked up.

388 SOLid RoLLeR

well thats what kinda scares me. i dont want to put some race gas in one day to see and the motor makes more power than with less octane. I wanted to make sure it makes no more power on 94 than it does on 92. Or am i wrong about octane...... will any motor make more power on higher octane?? is it c12 or 16 or whatever its called...?

388 SOLid RoLLeR

how is that 396 anyhow? tell me about it... im looking forward to my motor..

racerns

No, just increasing Octane will not make more hp in any motor. That is why I laugh at people putting premium in their cars that only need regular, it is a waste of money and may slightly hurt performance. The octane rating is just the measure of the fuels abitily to resist knock or pre-ignition. For peak performance you want to operate at a point right before the knock limit. There are many factors that can effect this but compression ratio, spark advance, and combustion chamber design are the main ones. In todays cars, if they say they only require regular gas, then most lilely they don't have a high enough compression rato or spark advance to take advantage of high octane fuel.

Who is going to be doing your engine tuning? This is where you will be able to play around with spark advance. You can optimize you car to run on 91 only by running less advance and when you put in higher octane you not see any difference. If you optimze spark advance to run on 93 you will see higer output, but when you had 91 in the tank you may see some knock spark retard that would hurt performance some, but should not do any damage. A good engine tuner should be able to help you there.

My 396 is still a hydraulic set up, check here for all the specs http://www.mycar.net/mafb/registry/detail.cfm?id=18

I did a baseline dyno with my old setup ECM tune and only 600 mile on the engine. It put down 432rwhp and 424rwt here is the graph http://www.mycar.net/mafb/registry/15/18/base_dyno.jpg
After I get the fueling tuned in and some more miles on the engine I think it will be around the 450rwhp mark. I also have a MAP drop problem I need to solve.

388 SOLid RoLLeR

oooh yeah, i kinda forgot about the tuning aspect. that makes perfect sense to me. im going to have the accel Dfi system soon, thats what im going to use for the tuning. the shoppe is very experienced in tuning and it shouldnt be a problem. A dyno is also the next unit to the shoppe so access is simple. Thanks for the info, now i feel comfortable abut the compression ratio. He also lectured me a bit about static compression and dynamic compression, so im getting a grasp of the info about compression ratios. I just wanted to make sure the car makes the most power on 92 octane, and no more on 94. that way i can use 94 just in case and ill know it wont ping for sure. i think the knock sensors are going to be teflon taped and desensitized in the computer tuning as well because of the solid roller setup.

How aggressive is your cam in the 396? what valve sizes did you use.?? oops just noticed the link... going to check it out =)

thanxx :cheers:

388 SOLid RoLLeR

a few questions about your setup on your GS Camaro. First thats a sweeet car!! and motor too! About your timing chain... i was advised the stock 93 chain wont cut it. He told me i have to convert to a 96 stle LT4 chain, requiring the better opti, timing chain cover etc.. So i bought a LT4 chain from Gm, 95 style timing chain cover and 95 style opti. Will the stock LT4 chain cut it??? i heard its real strong, i also hear its weak. i get kinda worried about 7500 rpm shifts. This is a street car and wont ever see slicks or drag radials, mostly quick shifting while highway racing.... dunno if that makes it easier on the motor or not.. What do you think?

Heres the beef.... i paid big $$$ for the LT4 chain set. I use a mezziere pump and realized that the only reason why its expensive is cuz of the water pump drive gear... i use a mezziere!!!! i dont even need that. If its not durable enough for my motor i want to go to a dual roller, and i hear its real cheap.. i just cant get any info on what chain will work, which is strong enough etc... can you help me out??? :cheers:

gkull

Niel - do you have any idea why your first motor failed? I can see from the picture that you had nice rods. I also saw that you use Crane Cams. I'm using something simular to the next higher duration than yours in the solid roller model. I had motor failure a couple of years ago and I removed the heads and intake and threw the rest in the dumpster.

Solid roller - when I first put my motor in I set the rev limiter to 7500. I have a brutal shifting 4 speed auto. I have 315/35/17 tires. It didn't take me very long to figure out that no street tire I ever found could handle WOT shifts at over 7000 rpm. In fact i had a few experiences of total loss of control on the 1-2 shift and to a lesser extent 2-3. I think that you will find out just like me that high rpm motors are not totally functional on street tires.

racerns

Sounds like the same thing I did, whole bottom end trashed. The rods where Childs and Albert. It failed on the big end, we are pretty sure it was a bearing failure of some sort, the crank was pretty blued in that area. After coming apart on the big end it then ripped the wrist pin out of the piston and mayhem ensued :eek: All happened at 6200 rpm in 4th gear coming into Canada corner at Road America. So far I am pretty pleased with the Crane Cam, I flirted with the idea of going solid but thought a lower rpm motor might last a little longer.

racerns

388 - Thanks about the car, not always sure how Vette guys will react to it. As far as the LT-4 single roller chain, it has worked fine for me but I am not spinning near as high as you plan to. If you already going to the Mez electric pump I would go to a standard SBC double roller chain. It will require a little clearancing inside the cover to fit but not a big deal. See if you can return the LT-4 chain. Good luck.

gkull

Quote: After coming apart on the big end it then ripped the wrist pin out of the piston and mayhem ensued

i have a collection of blown motor parts. Mostly from sprint car motors and some of my street cars. It's often hard to tell what happened first:(. the trashed block that I was refering to was a splayed cap 355. I think that maybe a solid roller broke durring a full power shift 3-4 at 7000 some rpm @ 130 mph. Because I heard a noise just before it cam to a screeching halt. The block was broken in the cam valley area and rods were snapped off.

I was actually sad :sad:

388 SOLid RoLLeR

i think ill have to see if i can return it. only problem is that it was special ordered from the u.s and took 2 weeks. Also i get managers cost on parts so they wotn be happy to see me returning anything, lol. I think double roller is the way to go, if i can't return the lt4 chain then ill try and sell it to someone. i dont think i want to take any chances. I agree with you about the 7000 rpm shifts breaking the tires loose, but i believe it would be more of a problem on an automatic. powershifting is another matter and i dont plan on doing that or id be sliding off the road. I dont care too much for off the launch, as ill be trying to save my tires mostly anyhow... 285/30/19 on an 11 inch wheel. im expecting the tires to break at low speeds anyhow but im building this for highway, and top end running only. hoping in a few months a video of my c4 doing 200 mph+ on a highway will join the one of the f-40 on Kazaa :eek: :cool: :D

vader86

If i remember correctly, GlockLT4 had a 383 LT1 with the LT4 hotcam and ported everything, so i guess thats a fair comparison.

I think he was running high 11s:1, Id suggest running a search in C4 Tech for all of his engine threads, they should be archived.

Id have run the search and put in the facts, but i'm on dialup and not too patient. :D

I just wanted to throw that info out there.

JUAN J SANCHEZ

I run 11.5:1 on a old style 406 with aluminum heads and a flat-top piston pump gas on the street. Your cam plays a big role in this , engine coatings also help, evans coolant and the rest of your cooling system, small combustion chambers with flat-top pistons to achieve high compression are the best way to run pump gas and high compression. Flat-tops promote flame travel across the top of the piston therefore reducing detonation possibilities. I've also seen 12.0:1 on pump gas! You need the right combination of parts.