nitrous2fast

iTrader: (2)

Do you realize that 580 HP in a 4 banger is different than 580 in a v8?

nicksevo

Errm not rilly I will try to look it up and understand but if you would like to educate me I would appriciate it hp is hp to me...it seems easier to squeese it off in a v8 with a boosted/sprayed platform and yes as I said I'm not aiming for the hp numbers but I want a nice car I can drive daily or whenever I want( weather permiting) and still know when I punch it I am going to be able to get up and go.

And once again sorry if what I'm saying seems dumb but if I have a car that can run a 11.4 1/4 at 475 hp. I would rilly want to push it I rilly want a 10 second car and idk if I figure it right but if I get about 580 with the weight the car sits at I can see it going 10s and I think that would be enough for me....at the moment but you always want more power.

I just don't get why u can cram a lot of boost into a low compression motor ( bring the compression high by doing this) and make good lasting reliable car but if u start off with a higher compression and add some boost ( increasing compression) why one would fail over the other. I know squeesing the air makes it hot but I figured its like already haveing some boost in it in a higher compression motor. But I have never worked on a higher compression motor before either so I'm am just learning ...I've always used a low 8.5 :1 compression motors and crammed them full of boost to get what I wanted

Wicked94Z

iTrader: (26)

thicker headgasket and meth will not be an issue. you could touch the chambers as well as a cheaper alternative to new pistons.

nicksevo

Sorry for a nothernewb question...chambers?

Lawhead

iTrader: (14)

Combustion chambers.....

nicksevo

Kinda what I figured ... but I dident think ide drop enough to run boost still...even doing it all I might be lucky to drop to a 10:1 compression at the max I would think....correct me if I am wrong

ahritchie

iTrader: (1)

You've already been told how:

1. Biggest intercooler you can get
2. Meth/water injection kit
3. Boost retard ignition
4. upgrade the fuel system

Done

Or just put some dished blower pistons on it.

ahritchie

iTrader: (1)

Not to be a dick, but sounds like you need to do some more research on forced induction; because you don't understand how it works at all by your above post...any motor has a static compression ratio...that means it does not change. A 8:1 compression turbo/sc motor always has 8:1 compression no matter how much boost is thrown at it...30#s of boost it's still a 8:1 motor. As mentioned by others, the compression ratio is a mechanical calculation. The only reason lower compression is used for boost is to prevent detonation from the higher fuel/intake charge temperatures due to the much greater heat of the air/fuel intake charge caused by being compressed by the turbo/sc. All a supercharger does is increase intake charge DENSITY....not affect compression. I would do a lot more research before you tackle this project.

gregrob

iTrader: (8)

Wrong.

ahritchie

iTrader: (1)

You are wrong; can't confuse compression and cylinder pressure with EFFECTIVE CR....seems like some here don't understand the formula for effective compression ratio comes about from the concept of mean-effective pressure, (which is optimistic in how power is scaled with comp ratio). There is a big difference in CR and EFFECTIVE CR of a boosted motor;

The OP never mentioned anything about EFFECTIVE compression ratio of boosting...just regular ole mechanically measured CR.

The typical equation used is,

CReff = CRstatic*(1 + Pb/Patm)

where CRstatic is the static compression ratio, CReff is the EFFECTIVE compression ratio, Pboost and Patm are the boost and atmospheric pressures, respectively. So for the LT1 with CRstatic = 11.4 and Pb = 8 psi (?),

There are calculators out there for this.
http://www.gtsparkplugs.com/Effectiv...ssionCalc.html


CReff = 11.4*(1 + 8/14.7) = 17.60

Anybody doing a FI build needs to do LOTS of research is the point I'm making.

gregrob

iTrader: (8)

It changes the effective compression ratio... the same number that is used to determine a fuels required octane.

You can argue semantics if you want, but I've seen it done in real life.

High boost on low compression or medium boost on medium compression can be done with the same fuel...

gregrob

iTrader: (8)

I definitely agree about the research tho!

nicksevo

I understand what your sauing I have just never done a higher or mid compression with boost as stated before I usualy am in the low 9:1 at the max...but that's a 4 cyl with 33ish lbs of boost to helop me push the car to the 500+ hp/tq. So I understand boost but never thought of boosting a higher compression motor before...I've always swapped pistons with a big dish so that I could cram boost because I can always change the boost for more or less power ( ie: easier for me to tune it and flash to diffrent tunes with just a boost controoler)

I just figured presure is presure...u fill a cylinder with a dencer charge it is going to make the compression higher which just game me the idea to do a low boost higher cr motor.. which would give the low end power for normal driveability and still have the great t/q curve I like.. that's why I asked here trying to get information weather good or bad...I understand and geting great info here btw that was a good read and i appriciate it.

And I'm my above post about making more cr I was talking about effective compression from what I am reading that's how I was thinking. I know the cr stays the same but the amount of pressure if what I was thinking I guess...thanks for the correction. Nick

ahritchie

iTrader: (1)

Unless you are a tuning guru with years of FI experience I would not boost that 11.5:1 motor....475hp to the rear wheels N/A is nothing to sneeze at even if it will be slightly less without a carb. That should be capable of 10's with right suspension/tires/trans. Sell the SC and buy some tires/suspension.

Or build a "proper" boost motor with dished pistons to lower CR and boost the **** out of it with 12+lbs and not worry about blowing it up and make 650+ hp....and spend lots of $$$ in supporting mods to do so.

gregrob

iTrader: (8)

Just spray it

wrd1972

iTrader: (12)

^ lol I knew it was coming.

nicksevo

Spray was an option for it also but boost is my favorate lol. Spray scares me ...seems like danger although I know boost is probably as bad on it as spray.

Btw the car is not mine yet I was just seeing the options for it as of now before I purchesed it.probably wait and just get a turbo ls1. But 4800 for a car I like that's already in the low 11's that just needs painted seemed like a good deal

ahritchie

iTrader: (1)

LMAO "just get a turbo ls1"

nicksevo

Why the laugh? I like the ls platform better but the lt for the price is pritty good deal

gregrob

iTrader: (8)

Its a shame you can boost a stock 4.8 or 5.3 to 600-700 HP reliably but apparently this "built" LT1 wont take a few pounds of boost.