bruthaboost

I was talking to Bryce at Alamo autosports in Arlington about what grenades engines all things being set up right. Bryce was telling me cylinder wall flex is the downfall of enignes (even properly tuned ones). This I think is generally known. He further told me horse power is the cause of the flex. This is where things get fuzzy for me. I thought hp was a function of psi and psi is the cause of wall flex. He was telling me 320 whp is the limit of nonsleeved blocks. If this is the case then around 12psi (drag kit) is the max psi for the vtec blocks and 17 psi for the LS blocks. Can someone clear this issue some. If 320 is the most I can run on a non sleeved block reliably, then I won't bother getting the map sensor upgrade for the Hondata. oh yeah I'm running eagle rods, pistons, oxide coated valves.

Sorry for the long post

mercury

You've pretty much got it. Too much cylinder pressure will make the walls flex. Cylinder pressure is created by both boost and compression. Since the B18C has a higher compression ratio than the B18B, boosting 12psi on a B18C will bring the max combustion pressure to very roughly the same pressure as boosting 17psi on a B18B. Very roughly, but you get the idea.

Detonation raises the cylinder pressure much higher than that of controlled combustion, so frequently it's detonation that kills engines.

VaporTrail

almost got it. Cylinder pressure (or combustion pressure) is directly related to how much fuel, ignition timing, cam timing, boost pressure, etc. It's all relevant. So, in theory, horsepower could be used as a greater gauge of cylinder pressure than boost itself. Really it all boils down to one thing - tuning. Detonation is your single most worst enemy, period. Great question and answers though!

Ray

so what about a GEM sleeved block, what would be the weak link at high Horsepower?

VaporTrail

in my estimation, if you have a GEM block, rods, pistons, and a balanced assembly, you have very few weak links. The next step in the chain would be the oil pump, which will sometimes shatter at power above 350whp. Prodrive and Toda have solutions for that. If you've done these things, I'd concentrate on making sure bearing clearances are exactly in spec, deburr the interior of the block for improved oil circulation, and have the crank access holes drilled out, fully cleaned, and tapped for plugs so future cleaning would be easier. You could go on and on in the block, but most of the things I outlined here will cover you up to insane power levels.

Ray

I'll be happy with around 350whp on my b20 thats reliable. Of course if the dyno puts up higher.

I'm thinking bout buying cam gears, do you guys think 210 is right for JUN cam gears?

bruthaboost

So if I understand this correctly, since around 320 whp is the most I can get on stock sleeves safely, I can go with a smaller turbo (read quicker spool up) and up the boost to my hp goal? Right about now I wish I would of resleeved. It's my only week point, however money had to go to pay tuition Still this should be enough...hopefully

Oh yeah, I'm definitely dyno tuning.


[Modified by b18bpwr, 6:29 AM 8/23/2001]

boosted97

What about using a GSR style girdle on the LS. Do you guys thing that may help with the flexing. Also what about a block guard. The reason I ask is I have an LS with a block guard, stock LS girdle and stock sleeves that is runnning 11.9s so I have to be getting near that sort of power output and I am always looking for ways to strengther the block.

VaporTrail

the girdle is going to save your bearings more than anything else. Z10 Engineering makes one specifically for the B16/18a/20. http://www.z10eng.com

DIRep972

iTrader: (1)

i dont know if buying the smaller turbo is gonna be the best idea... the bigger turbo will be more efficient then the smaller one and create less heat, it wont be working as hard to make as much power, the turbo will last longer.. and usuing higher levels of boost u have a better chance of detonation.. if u can make the same power using less boost and have lower temperatures that seems like the way it should be done.. u can always upgrade to a BB and spool a little quicker..

Ray

I thought the Z10/vtec girdle is to mainly safely rev higher. I'm keeping my red line at 7k still

earl

Pressure on cylinder walls is caused more by the side force of the piston as it is pushed down in the bore by compression. In used up motors, if you run a dial indicator down the bore, you will see the cylinder "baloon out" a few thousandsth about one and a half inches down from the deck. This "baloon out" cannot be compensated for by the rings at high rpm...therefore oil starts to get into the combustion chamber. The burning of the oil causes the detonation that ruins the engine. This is the reason block guards do not work as well as most people think. The reason the piston starts to push sideways on the way down is because of the angle of the crank as it spins off of top dead center. It naturally trys to push the piston sideways. Longer rods help to control this side force a little.
If anyone feels different about what I just posted, I would love to hear from you!
Earl

boosted97

Would it help if the block guard was pushed down an inch and a half or so instead of at the top? So you guys dont think the girdle would be of any advantage to me. Ive heard that Z10 products are almost impossable to obtain is there any truth to this?

earl

Even though I don't like them, I would install the girdle just as the mfg. says to do it. IMO Honda had a reason for building an open deck motor and I think they could have made it closed if they thought that worked better. Only an opinion.

Ray

I dunno, seeing how golden eagle sleeves are I dont get why honda didnt make their sleeves similar to that. Stock open deck sleeve just suck with turbos

VaporTrail

yes, but you're talking about two different apples there. Honda never intended for these blocks to see the abuse of boost. Hence they are open deck. Look at any factory turbocharged block, most of them are closed deck - and usually made of iron.

Ray

agreed but why not use make honda engine closed deck? what advantages do open deck have over closed deck?