Lagavulin

Brendan, what the...

Alright, that's it, this post merits an ***-kickin'!

<-- That's Brendan getting his *** kicked, again (..go ahead, drop another piston!).

A true static compression ratio of 11:1 is too much to run any appreciable boost, if at all. Take all the spark out as well as load it up rich as can be and the end result will be it running like a dog. Making matters worse, you wasted money on the supercharger installation since you're unable to utilize it's potential due to the too high static compression ratio.

If you're building a motor, either build it knowing you will or won't be supercharging it. 11:1 is good for a NA motor (..with the right cam), 9:1 is good for a supercharged one.

atb

Adam C. wrote:

I think we need to take it a step further Adam, "acceptable" is pretty subjective. I'd like to know if there is a documented failure for an N/A motor at a particular cylinder thickness (or thinness as the case may be).

At the time I put my block together, there was not the supply of blocks/motors that there is now. I looked around for probably almost 2 years for a spare block/core motor before I finally found the one that I did. So I went with what I had. I don't have a problem pushing some boundaries to see what happens. Without people doing it, we wouldn't have the forced induction motors that we have, or the strokers that we have. If I've got a verifiable and documented cylinder failure on my hands, then I won't run it "as is", but see if I can remedy it. If all I have is speculation that it may fail, then I'd still consider running it and seeing if she holds together.

Next point:
Does the nikasil coating provide the same (or better) strength properties as the native material? If I do as other's have, basically nikasiling the cylinders so I'm back to say .220" minimum (assuming it can go on that thick), does that equate to a block that has the same thickness all in alusil?

BC

Aw, now come on Lag. Don't be that way. Whats 5 or 6 psi among friends and a good standalone system that can properly run an engine that far out on the edge?

atb

The US Chrome website states that their NiCom coating can go .030" thick. That would tighten up my bores .060", which would bring even my thinnest cylinder way within even Reynolds conservative tolerances. Options, options.....

BC

INteresting. So we can consider this coating a structural addition?

atb

That's the $64K question. I'm going to call U.S. Chrome today and get their unbiased perspective.

atb

Millenium (nikasil) too.

Adam C

Well Adam, in any case my block comes out soon (87S4) if you happen to need one. My project is being built on a '91GT block that I happened to pick up.

blau928

Paul,

Thank you for waking Brendan up...

BC

Oh now guys, people are putting huffers of all sorts on 11:1 compression engines line t he S2000 and some other hondas.

blau928

Yes Brendan,

But what you do not hear much about is the grenading when using 91 octane gas and cranking up the boost like many of them do on the street.. It is possible to use 11:1 compression and use a low pressure system. However, you will then need to use 100 Octane gas, or octane booster all the time.. If you want a power adder at this high CR, then just add a shot of N2O3...

The formula to calculate this is a bit much, and I can assure you with 91 oct. you gonna ping pong at 5-6 psi... Unless you pour in a bunch of gas, and then the engine will run like crap, so why not decide what you will do before building the engine... It's a lot cheaper and better in the long run for you and your engine..

Not knocking anyone who wants to try though.. However, 30 seconds on a Dyno does not an all weather test make.....

BC

I was just speaking to the deck plating being a way to add a but of headroom and flexibility.

I'll have an appropriate 9:1 or so compression with a bit longer stroke - hopefully with a deck plate.

I can't change the 89 pistons much, but I am coating them for the headroom.

blau928

B,

At 9:1 you should be fine to add some more air and gas... It should make for a very powerful setup once properly set up..

Cheers,

rob rossitto

whew! thought lag was going to kick my ***... haha, sorry bc.... it's ok, I've got a wife for that, so don't worry, I get beat regularly (what are those devek L2 headers doing in the garage, rob? uh oh)

but just to be clear - I don't think nicom is a substitute for a real sleeve by any means... but it does provide a hard coating that adds metal/material/ strength/ so it'll reduce flex, and if flex is down, then maybe less cyl balloning/structural damage over time... but, on the other hand, sometimes if something is too hard/brittle then there is a cracking issue, so there's probably a limit (thickness) somewhere (.030"?)...

in any event, I dont' think I'd use nicom for as a substitute for a deck plate by any means either... just think it'll help a bit, and every little bit helps when you're out on the edge - to a point...

where that point is - depends on a LOT of stuff, but I suspect that where this block is for a NA application, it may be salvagable with nicom and a custom piston....