is 8.5 too low for daily driven?

[trbogsr]

I am about to buy new pistons rods and injectors. I got a damn good deal on a set of 8.5:1 pistons and AEM hyper rods. i forget what pistons they are, but i think that they arias or something like that. i was wonderingif 8.5 is too low for a daily driven honda. i was also wondering what the advantage of blockgausrd are versus re-sleeving the cylinders. i want to do it right and dont care how long it takes, i just want the damn thing to run effeciently. Also do you think that 310cc injectors are enough for the task? i just want to be a really fast daily driven car. not interested in full drag racing, but want to keep up with the supras around here. also, do you think that the profec b is a good boost controller, or should i use the apex avc-r? i also had pms in mind, but notsure if anyone has used it or is using it please give some feed back. last question, does anyone know the price of that 35mm tial wastegate, or does someone want to start a group buy? thanks for your help in advance.

daniel

[trbogsr]

forgot to mention that this is a 94 integra gsr, with a nos fuel pump, t3/t4 turbo, f-max intercooler and piping, greddy PE, ACT clutch, and vortec fmu.

[Bryan-96'GSR]

It's is a little low.. you could correct it with a tad thinner head gasket.. I would suggest 9:1, I'm installing 10:1 on my turbo, it's being resleeved as well.. I would suggest resleeving, you will not overheat as easily, they say "well we never seen the temp guage move with blockguard." If you don't forget, it takes a tad bit of heat to make a honda guage move, so yes you will be running hotter, I don't care what they say.. and you will overheat easier. Also Blockguards just keep the top of the sleeves more stable, what about the inbetween the top and the bottom? Where the most pressure in the combustion chamber exits? As you may know the mixture's highest pressurized point is not at the top, it's in the inbetween.. as well as your 1.58 rod ratio, most pressure is also moved more towards the sidewalls.. So though you could get away with running a blockguard, your beating your engine much more by not resleeving it. Or taking other measures to better equalize the loads on the walls.. I would also suggest you ask your engine builder to move the rings on the pistons up the most he could, and order a custom set of rods, just to give you a tad better rod ratio, as every bit counts, prolly end up somewhere around 1.62.

Bryan

[MarkC]

Bryan,

Please explain your reasoning on why you should move the ring-pack up further on the piston. I understand why you would want to move the whole ring-pack/wrist pin up to get a better rod/stroke ratio, but moving the ring-pack up also exposes it to more combustion chamber pres. This is one of the faults of stock Honda pistons and why they tend to fail under boost. After market pistons move the ring-pack further down on the piston skirt almost over the wrist pin to isolate it more from the extreme cyliner pressures. Maybe you know something I don't?

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Mark - Darth Boost - Turbo Mafia
98 Pearl Black GS-R, DRAG Gen. 3 Turbo
13.2 at 114MPH (GTech/Pro w/Drag Radials)

[rjaffey]

The highest cylinder pressure, not to be confused with side thrust, is at the top just after the pistons have past TDC. Detonation stresses the walls the most at or near TDC as well. I don't think the blockguard will cause the coolant temp to run higher, it will just cause the cylinder walls to run hotter at the very top where they need the most cooling.

Swapping head gasket thicknesses has to be done carefully in conjunction with piston config so proper quench (squish) clearance is maintained.

I also understand that compression rings survive longer when placed lower on the piston; farther from the heat and possible detonation stress.

[This message has been edited by rjaffey (edited February 17, 2000).]

[MarkC]

Pushing the ringpack higher also pushes the ringpack closer together which reduces the size of the ring lands. Also not good.

I would stick to stock Honda geometry unless you are 1fstgsr and have something spicey planned.

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Mark - Darth Boost - Turbo Mafia
98 Pearl Black GS-R, DRAG Gen. 3 Turbo
13.2 at 114MPH (GTech/Pro w/Drag Radials)

[Heretic]

8.5:1 is just fine. It'll give you a much bigger tolerance for tuning. Lower compression means you won't detonate nearly as easily. It's just not a problem driving with a lower compression ratio. Turbo may spool a little slower, little less power but you can run more boost. 10:1 compression on an FI engine doesn't seem wise, unless you're only going for a small amount of pressure or you never run on street gas.

As for the block guard, might as well just do both. I could have sworn my block guard went around all of the cylinder, not just the top/bottom.

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Ryan Earl
'99 Turbo SH
NTPOG - North Texas Prelude Owners Group
My Page

[Tomakit]

the new super street has a documented installation of a block guard. seems to only help solidify the top of the cylinder walls.

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My 'teg seems to know when i have $$, how bout you?

[trbogsr]

so basically it would be better to re-sleeve the cylinders? who sells the sleeves? i cant seem to find anybody who sells them. i havent tried real hard either. should i get new head studs? someone mentioned them to me but not sure the purpose. and will 310cc injectors be big enough or should i get bigger ones?

[Bryan-96'GSR]

Actually MarkC if you were to read it more carefully you would see I said to contact the manufactur to get a idea of how much you can safely move it up.. It doesn't terribly hurt things, as you would be moving it up as much as is safely possible.. Honda rings are actually pretty well spaced, if you were to speak with many builders you would see they do not go past the stock ring locations 99% of the time unless they have a real reason to.. Honda engines fail underboost for one reason, they were not built as performance engines they were built as effiecent engines, not something to slap 10 psi on.. and expect it to last.. so you should realize that. Only way you will get a better rod ratio without destroking or adding to the block is to move the ring package up.. that improved rod ratio would help you more than putting the strongest rods or pistons in there.. as you would see has been done on many cars with terrible rod ratios as the b18..

Bryan