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Discussion Starter #1
Hi guys!

Here is the deal. Before I wanted to bould a low comp engine and run mad Lbs of boost on it. Cool! But now after some reading my agenda changed. Now I want to build High compression engine, and run mad boost on it. (My goal is 25PSI)

What do you say about it? How about 8.5:1 compression engine running my desired boost? Obviously intercooling, fuel&timing managment, better internals will be involved. What else? Just tell me what you think!!!!!

Eugene
 

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In the world of turbocharging, an 8.5 cr is the upper limit. You will be able to do it, but I doubt you will be able to stuff more than 12-14 lbs boost into it. Remember that every 4 lbs of boost raises the static compression ratio by about one full point. At 12 psi you will have an 11.5 to one motor. That is manageable. At 24 psi it would be 14.5. That's a whole lot less manageable. I suppose it is possible, but of course fuel and timing will be the key. You will need LOTS of fuel and very little timing. I hope you plan on forged pistons, because nothing else will hold up. You will also require the HK$ head gasket. I think that it is possible, but you are walking on the fine line. If I were you, I would go with an 8 to one ratio, and about 14-16psi, and a 60-1/T3 hybrid. You will able to make at least 400 hp with that. If you want more hp, 7.5 to one, 62-1 turbo, and 20 psi. That will result in about 450-475 hp. Trust me, you car will be uncontrollable with that much power. Good Luck!!!!!!!!!!!!!

Ian
 

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Low end torque, turbo punch

> In the world of turbocharging, an 8.5 cr is
> the upper limit. You will be able to do it,
> but I doubt you will be able to stuff more
> than 12-14 lbs boost into it. Remember that
> every 4 lbs of boost raises the static
> compression ratio by about one full point.
> At 12 psi you will have an 11.5 to one
> motor. That is manageable. At 24 psi it
> would be 14.5. That's a whole lot less
> manageable. I suppose it is possible, but of
> course fuel and timing will be the key. You
> will need LOTS of fuel and very little
> timing. I hope you plan on forged pistons,
> because nothing else will hold up. You will
> also require the HK$ head gasket. I think
> that it is possible, but you are walking on
> the fine line. If I were you, I would go
> with an 8 to one ratio, and about 14-16psi,
> and a 60-1/T3 hybrid. You will able to make
> at least 400 hp with that. If you want more
> hp, 7.5 to one, 62-1 turbo, and 20 psi. That
> will result in about 450-475 hp. Trust me,
> you car will be uncontrollable with that
> much power. Good Luck!!!!!!!!!!!!!

> Ian

Sounds scary!! I've been into a continuing discussion with my son on the best way to build a 5.0 Mustang killer off the line, but still maintain that glorious turbo top end. There's got to be a magic combination of compression and boost that'll give me that low end torque from my turbo engine, yet not self destruct at high RPM when the turbo joins in. Guess I want my cake and eat it too. I'm not after out of sight boost, just that hard pull through the full RPM range. How 'bout swapping those dish pistons for flat tops? I'm thinking intercooled of coarse. If anybody else has insight into this, please input. Turbo motors are new territory to me, so I'm sort'a shootin' in the dark.
 

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Discussion Starter #4
I suggest reading Turbo magazine>>>

In the Januaray issue of Turbo and High Tech Performance they explain all the issues of finding the right compression ratio for your turbo engine and all the theory also.
 

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How do you spell Diesel!!??

> In the Januaray issue of Turbo and High Tech
> Performance they explain all the issues of
> finding the right compression ratio for your
> turbo engine and all the theory also.

WOW!!! If you look at the equivalent compression ratio of 8.5 cr and boost over about 14 psi you get into diesel engine compression ratios. Everyone understand how a diesel works? The thing compresses the fuel air mixture until it gets so hot it detonates all by itself. Thats why those things make all that racket and weigh about a bizmillion pounds. The way they stop the engine is to shut off the fuel. Anyone having second thoughts?
Merry Christmas,
Phantom
 

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D-I-E-S-E-L

> WOW!!! If you look at the equivalent
> compression ratio of 8.5 cr and boost over
> about 14 psi you get into diesel engine
> compression ratios. Everyone understand how
> a diesel works? The thing compresses the
> fuel air mixture until it gets so hot it
> detonates all by itself. Thats why those
> things make all that racket and weigh about
> a bizmillion pounds. The way they stop the
> engine is to shut off the fuel. Anyone
> having second thoughts?
> Merry Christmas,
> Phantom

Yeah, the old tractor down on the farm fell into the bizmillion catagory! But the 0-60 times sucked. Sure would pull stumps though.
 

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I like this guy - I'll only shoot him once - n/c

> Yeah, the old tractor down on the farm fell
> into the bizmillion catagory! But the 0-60
> times sucked. Sure would pull stumps though.
n/c
 

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Discussion Starter #8
So, is it yes or no?

Dudes, dudes!!!!!!!! I know we all are getting excited, but let us keep our cool!!!

Phantom, do I notice a bit of scepticism??? Why is that?

I might be dumb, but I will have 8:1 motor running 15-18 on street, and ~25 on the drag track.

My goal is to have rock-solid reliable everyday driven TRUE 400HP Rocket. Thou my goal is not to have dragster but more like a road-racing kinda car. I am plnning to attend one or two drag strips when I feel that car is ready to run mid 12s.

I am planning to do it with help of compleatly revorked stock sized engine. ( Forged pistons with specially located rings, gapless rings, special coating, titanium rods, blanced crank). Nicely made head - porting, polishing, valves, springs, etc. ~60mm trimed ball bearing turbo, into 3 exaust. Disently sized front mount intercooler. And of course TECII tuned to the balls, along with bunch of other little tricks.

What do you say? Will that be possible? I know it will take time and some Grando Dinare but never the less...

Eugene
 

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Re: So, is it yes or no?

> Dudes, dudes!!!!!!!! I know we all are
> getting excited, but let us keep our cool!!!

> Phantom, do I notice a bit of scepticism???
> Why is that?

> I might be dumb, but I will have 8:1 motor
> running 15-18 on street, and ~25 on the drag
> track.

> My goal is to have rock-solid reliable
> everyday driven TRUE 400HP
> Rocket. Thou my goal is not to
> have dragster but more like a road-racing
> kinda car. I am plnning to attend one or two
> drag strips when I feel that car is ready to
> run mid 12s.

> I am planning to do it with help of
> compleatly revorked stock sized engine. (
> Forged pistons with specially located rings,
> gapless rings, special coating, titanium
> rods, blanced crank). Nicely made head -
> porting, polishing, valves, springs, etc.
> ~60mm trimed ball bearing turbo, into
> 3 exaust. Disently sized front mount
> intercooler. And of course TECII tuned to
> the balls, along with bunch of other little
> tricks.

> What do you say? Will that be possible? I
> know it will take time and some Grando
> Dinare but never the less...

> Eugene

I'd vote yes, but only if you do it right like you plan (though titanium rods are overkill). 15 psi is fine for a 8-1 motor with a decent sized intercooler. to go higher would require race gas or seriously retarded timing. If you try to do it with low timing (less than 25 degrees) you will be giving up too much power and wasting your time. to run 25 psi be prepared to spend the bucks to run C-16 race gas. Plus even a little detonation at that level can easily crack a piston, even high dollar JE and Ross. Be very sure the car is tuned well, with a good knock detector-not by ear, before cranking up the boost. You realize all the stuff you just mentioned adds up to at least a 6000 dollar motor? sure would hate to blow it just so you can say you are running 25 psi. Timeslips are all that matter.The motor you described better see 11 second timeslips. 8 or 8.5 compression sounds good to me. forget trying to go higher and run lots of boost. yes you could make it live, but it would be better to make it right. I hate to get on a rant here, but what's all the talk of 60-1 turbos now? just a few months ago everybody wanted a hybrid, now they've jumped to full 60-1 t4's or bigger. not that they are bad, but now we are talking serious race turbos that people are wanting to run on their daily drivers. I'd hate to see someone spend close to 2 grand on a ball bearing t4 then find out it sucked at anywhere below 4000 rpm. or even worse that they didn't have a motor to support that kind of turbo. I think I'm really just scared I might run across one of these wickedly fast z's once I finally get my car back together :)

greg
71 240z

greg
71 240z
 

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Re: So, is it yes or no?

When I refered to the 60-1 and 62-1 turbo's, I thought that I made clear that I was talking about T3/T4 hybrids. This means that the compressor section would be the 60- or 62-1 and the turbine section would be a T3 of required trim. These turbos, though slower to spool up than the stock T3, will work fine on a well prepared street motor, and are required for engines producing the kind of hp we are talking about. The ball bearing option is nice, though very expensive. It will improve the turbo's response slightly.

I completely agree w/Greg that a motor w/8.5 to one cr will require high dollar race fuel to survive at boost levels of more than 15 psi. I recomend 8 to one. It is nice to say that you have built a motor no one else has done, but no one else has done this setup because it is risky. I agree w/ Greg that you will be spending BIG $$$ on a motor that could become a pile of molten metal in a matter of seconds if something goes wrong. Take this advice if you take any at all:
you are about to make a very large $ investment in your engine, don't risk blowing it all for a time slip.

Ian
 

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Discussion Starter #11
> Hi guys!

> Here is the deal. Before I wanted to bould a
> low comp engine and run mad Lbs of boost on
> it. Cool! But now after some reading my
> agenda changed. Now I want to build High
> compression engine, and run mad boost on it.
> (My goal is 25PSI)

> What do you say about it? How about 8.5:1
> compression engine running my desired boost?
> Obviously intercooling, fuel&timing
> managment, better internals will be
> involved. What else? Just tell me what you
> think!!!!!

You should also think about getting a ignition timing computer that is made for turbo/supercharging that can auto set your timing so you won't go to far advanced/retards when needed. MSD makes one just for turbo/supercharged setups. It should help your engine live with lots of pressure but do more research about how much the L6 can take before you break something. Good luck...

> Eugene
 

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Thanks ya'll

> You should also think about getting a
> ignition timing computer that is made for
> turbo/supercharging that can auto set your
> timing so you won't go to far
> advanced/retards when needed. MSD makes one
> just for turbo/supercharged setups. It
> should help your engine live with lots of
> pressure but do more research about how much
> the L6 can take before you break something.
> Good luck...

You answered my question guys. Sounds like 8to1 is the safe limit. Thanks for the advice. Sorry Phantom, couldn't resist!
 
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