Pro Stock John

iTrader: (34)

I believe that 900rwhp is possible with 93 pump gas and no meth.

An 8:1 540bbc + a2w, etc.., should make huge power.

Your goal of 1100rwhp with 93 pump gas is interesting, and I look forward to reading about your progress over the next 12 months. I'd plan for 96lb injectors I think.

Nickn20

not saying it cant be done or hasn't or it wont run, but I do beleive there is a gain in power to be had going to a bigger exhaust.

question for you, where is your wastegate bypassing to? atmosphere or the down pipe? turbos are slightly different than a blown app. all in all I think we are on the same page though

Got Me SOM

iTrader: (2)

If I was gonna rip the block apart I would lower the compression more than a half point, you are probably not going to see any gains with a half point drop. Drop it to 8:1 and run 21 psi, that should be fun.

Look forward to seeing you run your car at the strip.

Bryan Wilkinson

iTrader: (1)

Perhaps that is the key here. Maybe lowering the timimg a couple more degrees, would help the situation. Just remember, You are not running 10:1 and neither is Harlan. That is definately part of the problem here. I have the absolute best parts money can buy from that standpoint. I believe you could run 30psi as long as the Compression Ratio was lowered.

Some sort of cooling is needed. I just dont want to use anything that I have to put in the flow. NOS on the IC, or a C02 pipe on the intake side. I am not seeing any detonation or knock, so I can only assume that cylinder pressure casused the gasket to give way.

according to JE Pistons, They are telling me with a 4.00 inch crank, and 6.125" rods, on a 4.127 diameter cylinder, 9.5:1 is the lowest compression that I can have. If any pistons experts reading this have any other suggestions I am all ears. I am taking JE at their word, but I am also open to options.

If anyone else is reading this, read the specs above before jumping on me.

smokinHawk

iTrader: (48)

i wouldnt take them at their word if they told you that, unless there talking with shelf pistons. What dish pistons would make the 9.5 CR.
plush you can always increase the chamber of the head or add a thicker gasket, if that fails switch to a shorter rod.

blackz93

iTrader: (2)

So Bryan, did it blow the gasket, or just lift the head?

Pro Stock John

iTrader: (34)

Or did it burn the gasket.

MIGHTYMOUSE

iTrader: (59)

i melted aluminum out of my head before i burned through the steel gasket.

Bryan Wilkinson

iTrader: (1)

The dish is -29cc, and the chamber in the head is 72cc. 9.5:1.

What everyone seems to be missing here, like with Johns statement, sure with 8:1 CR I could run 30psi and not lift the heads. So could Harlan. Plus with the LS6 heads, these are not optimal for blown applications because they can move due to the thin deck. thats why AFR's have a thicker deck.

There is a potential problem here with the 427, and any experts on the site can pitch in, with a 427, and a 4.00" stroke, piston speed in increased. So it is important to keep the rod length as long as possible and in this case is 6.125". So with a 4.00" stroke, and 6.125" rods, I am being told that 9.5:1 is the absolute lowest CR that I can go with the 427 block. That is via the piston, This was a custom built piston, that is 4.127". The design went through their engineering dept. My guess is JE probably knows what they are doing.

Notice that everyone else here without a 427 has a shorter stroke, thus more room so even with a 6.125" rod you can get 8:1cr.

Now with the new heads, they just got the castings back, and with the thick deck on the bottom of the head, 5/8", they think they can go to 76cc in the head. The concern is the shape of the chamber and will it promote an efficient burn process.

Perhaps I would have been better to go with a 350CI instead of a 427 with a 3.00 inch stroke.

Bryan Wilkinson

iTrader: (1)

That's what Im talking about, Git -r- done!!!!!!!

Pro Stock John

iTrader: (34)

Yes, that 4.000 stroke does make piston selection more complicated.

rons 00z

iTrader: (10)

have you experimented with ceramic coatings at all?
heres a link that give their explanation about why and all that
http://www.swaintech.com/autolc.html

deffinatly keep it up it's an awsome goal.

LTLHOMER

iTrader: (10)

I see lots of these once you take that thing to the track:



It's a good thing you're in it for the dyno glory, because if you were racing, you'd need spare motors for each pass. I'd elaborate but you wouldn't listen anyways.

I will give Bryan one thing though...he's proved that you actually spend more trying to build a pump gas motor (which is supposed to save money I guess???) than just buying the damn c16 in the first place and making the motor live.

S_J_H

Bryan Wilkinson,
You are so dead set on this pump gas thing you are getting lost in your own fog.
Cylinder pressure is HP! , unless it is uncontrollable pressure spikes from detonation.

Lowering compression and raising boost to make more power, would mean MORE cylinder pressure.
And I do not think you are anywhere near the absolute mechanical power limit of these motors.

You certainly may very well have found the limit for pump gas at 10.0-1. And I am amzed you have gone that far, but to much cylinder pressure is not the limit. Octane tolerance is.

I would suggest you use a good engine simulator to understand this better in your power quest. Check out how the B.M.E.P. changes as you raise and lower compression and add or subtract boost.

Steve

rons 00z

iTrader: (10)

how much power do guys make for the pump gas drags?

Pro Stock John

iTrader: (34)

Ron, when you consider the power level of the PGD cars, also factor in their raceweight. A number of those cars were <3000 raceweight I would guess.

69firebird

iTrader: (14)

yep, they are some bad *** cars thats for sure

id bet most of those are race cars made to drive on the street, not the other way around.

rons 00z

iTrader: (10)

thats true but powerwise say at the crank shouldnt change because of the weight. after all he is talking about HP and not timeslips. but yes if his car weighed as much as a PGD car i think he would beable to hold his own as long as he can drive like those guys.

Pro Stock John

iTrader: (34)

I bet Bryan is more like 3700 raceweight, maybre 3800. Makes a difference.

nitrorocket

iTrader: (12)

Bryan, There should really be no difference between a sbc and an ls1 as far as piston in your case. My last 421 had the same bore and stroke as you. When Monty went from 11.25:1 to 8.5:1 compression, he used JE pistons. My point is they HAVE to make them. I would try calling around also.

Wiseco makes a piston!!!

K397A125 has a 32 cc dish! Try that out on your compression calculator!

(PAGE # 8)
http://www.wiseco.com/PDFcatalogs/AB05_chevy.pdf

I think the rep at J.E. was smokin' something. I am sure if you check around, you can even find a larger dish then 32cc with a custom piston.