Okay.. so it's about.. I dunno 3:12am right now and my brain is half off, but the other half is still thinking. (I wish it wouldn't)

Welp... here are my thoughts...

People generally stick with a 15% Pulley because it is considered "Safe and Effective". As to my understanding, it's generally not a good idea to go up to a 17% or a 19% pulley due to supercharger efficiency at those prologned higher RPM's and not so much because the boost is too high. (?)

What if someone were to stick with a 15% pulley and use a thinner head gasket?

If the block and internals can easily handle the increased cylinder pressures of a 19% pulley, then wouldn't that be a much more efficient way of going about things? Cause you wouldn't be spinning the supercharger any faster, so it would remain efficient, but you'd still be getting the higher cylinder pressure which would in turn give a higher power displacment. (?)

We can't be too concerned about Pre-Ignition due to the fact that the ECU would compensate for timing.

I dunno... any thoughts?

Note: Lets not throw this into a long-heated debate about supercharger pullies, there are plenty of threads on that.

 

it might work but there are a few things to think about. first is there enough clearance for the valves to the piston tops?? if not then you will need to notch the pistons or bend the valves!

then you get onto the dept thing. now you are right the Ecu should protect against dept by pulling timing, but i would rather have a safe setup engine thats not going to dept rather than one that might!

personally id looking into making more power form the SC/heads/cam/intake/exhaust/intercooler and if you are still left wanting, drop a little N2O in there!

thanks Chirs.

 

M7 16% Coming in next week.

Webb Motorsports Head, Intake Manifold, and Intercooler Pieces in a month or so.

Ultrik Camshaft sitting here on my desk.

Megan Racing Intake and Exhaust already on my car.

ALTA Ver 2. Intercooler coming in next week too.

I'm not too big of a fan of Nitrous Oxide... I'd abuse that like no other.


The reason I'm asking about the head gasket is because I'm getting ready to do the upper-block and so I figure if I'm going to be needing a new head gasket anyway, then I should consider the variables within getting that head gasket.

 

one of M7s head offering shaved some thickness off the head to give a slight increase in compression. Some love it, some not so much so. I think it all comes down to the timing pull that you mentioned. While it will keep the engine happy, it will suck the power right out of your motor. If you have good gas it might work. Give Don at DMH a call, he's had some experience tuning (trying to tune?) increased compression ratio motors.

Matt

 

I couldn't see you gaining too much more compression and efficiency. 1cc/cylinder? Plus you would be minimizing total air volume during pressurized intake stroke, thus increasing air temperatures anyways....hmmm. Easier results with decking the block or milling the head or a dyno/ecu tune?

Jeremy

 

I have access to a Dyno and am gonna tune away to my hearts content. It's not so much that I'm looking for an easy or cheap way out of anything or trying alternate methods.. what it is, is that I'm going to replace the Head Gasket anyway, so there won't be any additional cost if when I DO install the gasket, that is thinner.

 

Wait... you don't know?! Matt....



Matt....


Man... I don't know how to take this. I need to go for a drive.. I'll be back later.

 

is the depth of his ignorance! I'm very, very wise...

Matt

 

i thought s/c 'd engines ran low compression for a reason . are we gonna run s/c or norm aspirated? cramming more in and compression ratios seems might be two diferent things ?

 

Yes, I understand the concepts. What I guess I'm getting at is that I know that the stock internals can handle the increased cylinder pressures of having a higher boost such as with the 19%. I have no intrest in running a 19%, so seeings the boost will remain at the 16% that still leaves me some room to increase cylinder pressure.

In reality I guess the only way I'd ever truly know if it's a good idea or not would be to run both setups with the exact same variables and Dyno them...

I neither have the time nor the money for all of that, so I guess I can put my troubled mind at ease... oh.. woe is me.. woe is me...

 

LOL. Does Nokturnal win a prize or something??

 

we should let the markets decide!

Also, I'd guess that you'd want a way to keep knock at bay... Either good gas, frequent uses of Sea-Foam, or some water injection. My car pings like crazy if I let the carbon build up or the plugs go south. But we have some crappy 91 octane gas here in CA, that's for sure....

Matt

 

and whats the reason for the low comp???? its dates back to the old SBC and BBC days with the HUGE none intercooled blowers sat ontop of the engines. they had to run low comp to stop the engines blowing up!

times move on & tech moves on! most turbo cars run over 9-1 comp. ratios these days and you can run alot of boost form them (how about over 800bhp form a 2.3ltr on pump fuel??? i can post a link to engine dynos to prove it).

and clearly if you think comp. ratio has nothing to do with a engine just cos it has a SC on there then you a bit of learning to do.

thanks Chris.

PS sorry if that sounded a bit harsh. dont mean to offened.

 

R56 is turbo and have much higher compresion rate.

It's all about the safety. If you have brave you can go down.

 

and this massivly cools the intake charge compared to port injection on the R53. That's why it has over 10:1 comp ratio. There's a lot that goes into knock prevention in motors, and just cause one engine does it doesn't mean another engine can run the same boost, comp ratio and octane. I'd bet that Honda has a FMIC, and probably water injection too.

Problem with our cars is that it's so close to timing retard in stock form that there's little headroom for changes without doing something else to cool the charge or supress knock.

Matt

 

i guess i'm saying if it pings now and they do then why increase compression just to ping more? not the increase in boost but the physical decrease in clearance ; seems detrimental . look as posted above ; the loss in chamber size due to carbon build up {hot spots aside} allows for ping in some cars .

 

"Back in the day" there really wasn't an effective way to alter Ignition Timing, my crappy 91 Cali gas will only be as effective as the ECU's timing will allow it to be.

 

mini do thicker gasket set as well? so how about going bigger? on a big valved head, more air and fuel going in so why not? or am i being daft

 

Doesn't change the volume of the cylinder (piston still moves just as far and is just as big) it just changes the size of the area the charge is stuffed into aka, compression ratio.

 

Under boost you'll get a skiff less of charge stuffed in, and as a result a skiff more compression. I think they'll offset and not amout to much of a gain or loss.

With the BPV open and you're spot on Amg6975(swept volume stays same always).

DmOcRsI did you finally get all of your stuff bolted on with that slim head gasket? How do you like your Webb cylinder head with your Ultrik cam?

Jeremy

 

going bigger will result in more quench and this can lead to dept. although its queit popular in the import world.

Chris.

 

sorry not up with this tecno stuff, is quench cooler, i am thinking that lower head pressure = lower temps = less fuel required for cooling,
and a more efficent burn = better power
but will a reduction in compression loose me lots of hp and torque?

so what i gain on the swings i loose on the roundabouts?
or is the real benifit a cooler running engine and less back pressure on supercharger

not sure on dept

 

I know this is old but I just had to reply. With all due respect this is the dumbest misinformation I've ever seen. If anything it's the opposite. Same reason why carbs make more power than fuel injection. The more time the fuel has before it goes into the combustion chamber the more it can cool the air. Direct injection does nothing for cooling the air. There may be other reasons that I'm not gonna get into that the direct injection allows higher compression but cooling is NOT one of them.



As for this thread. I completely agree with your thinking. I've been researching this for a while now. Raising compression and running 15/17 would be a perfect combo with good gas and meth injection. I'm running higher compression right now with no problems