250 twin turbo garrett t25 project

[Anonymous]

jus had a couple of questions.

1. can i somehow use the engines oil pressure to lubricate the turbos ? i read somewhere about putting a T fitting in an oil line coming from the engines oil pump but im not sure, does anybody know if this is possible.

2. can we use the heater core lines to run coolent to the turbos?
to me this seems like a good idea then again im new to this.

3. since were going with a draw through setup will the stock carb work?
i read around and to me this is supose to work just fine.

were using a 250 block and the idea is for this to be a low as possible budget build.

thanks

 

[Bort62]

1.) Yes.

2.) Sure, why not?

3.) Yes again. However, you talking about using a single carb? Seems like w/ twins you would want to run 2.


But, Ill say the same thing I say every time. Why twin? Single will be lower budget and work better.

 

[wallaka]

You picked the right size turbos, at least.

 

[Anonymous]

how much boost do you guys think the stock block can handle?

 

[addo]

It's not the block, it's the head gaskets that let go. Probably a perfect setup would be ½" studs, scraped faces and O-rings; no gasket.

 

[wallaka]

Depends on how well the head and intake flow, since boost is just a measure of how inefficient they are.

Linc had his to, what, 20 psi or so? If you can keep head gaskets in it and keep it from detonating, the stock block is pretty much bulletproof.

 

[Anonymous]

yea thats what i meant head gaskets and everything b/c we want to run this engine with a safe amount of boost, its not for all out max power its just for fun.

and thanks alot guys with the help we really appreciate it, its nice to talk to people who know what they are actually talking about.

 

[addo]

...its nice to talk to people who know what they are actually talking about.

As opposed to the forums where everything descends into shouting matches and incomprehensible BS?

A really good, reliable fuel and spark control is going to be a great asset. I'd be pretty wary of anything other than light boost before you have something in place there. It'll help economy also - and who can ignore that, now?

 

[Bort62]

I keep shouting at the computer, but it doesn't seem to help.

From my own experience and others around here, 10 psi is probably the limit of "safe boost" on a stock motor w/ intercooler and appropriately moderated spark advance.

Linc ran up to 20, but he wasted a few pistons. Kirkallen has lifted a few headgaskets @ 15. I'm running 9 and even with tuning not totally worked out and detonation here and there, I still haven't broken anything.

 

[Bort62]

Oops. Now I just cursed myself...

 

[Anonymous]

well we're running a draw through setup we wont have any intercooler, esp since i heard about backfires and explosions. so 7 should peobably be the limit with me right?

 

[addo]

I have to admit some skepticism about the "intercooler with draw-through" horror stories. The internet seems to foster some popular rumours that are largely unfounded (propane in the aircon and maximum tyre pressures are another two).

What it may well introduce, is a further degree of unpredictability into your system - and that isn't good. 7PSI is heaps; even three or four pounds would be a pleasant "extra". To impress boneheads, you could always get a gauge calibrated at double the actual pressure!

Note that the hardcore turbo guys here are tending to get into wideband analysers for the sake of accurate tuning; pehaps one in the budget sooner than later, would be a good plan.

 

[XFlow_Fairlane]

what I have heard isn't so much backfires as puddling of fuel in low spots of the intercooler and piping. by removing the heat from the air charge some of the fuel will condense. I can see this not being a big issue on a drag car that is WOT most of the time (intake velocity is high enough to suck up any extra fuel) but in a daily driver or street driven I could see it puddling on coasting or other part throttle low load instances.

Really like addo said.....8 pounds will add alot to a 200. you can also run pretty fat on the fuel and heavy on the retard to have a huge safety margin and still have a decent power gain. 10-90 90-10 deal....

10 percent of the effort will get you 90 percent of the power and the last 10 percent of the power will take 90 percent of your work.

 

[Bort62]

When I ran w/o an intercooler, I couldn't get much past 4 psi w/o significant detonation.

I didn't really spend much time trying to tune @ that point however, so take that w/ a grain of salt.

If I was going to do draw through I would try to get away w/ about 7 PSI with some heavy water injection.

I am running a bone stock 200 as well.

 

[350kmileford]

What's the max boost one could run without ringing the block? I understand there are many factors to consider, such as compression ratio, timing, etc... but at a standard 8 or 9 to 1, what would you guess?

 

[Bort62]

Guess? 20 psi.

And that's a pretty worthless guess... But it's been done.

It really depends on so many things.

 

[Anonymous]

some pics of the current build

and a pic of the car

 

[drag-200stang]

ss400,

Hey, does that thing have a straight axle in it? I would take the extra time and build a mock up of your engine bay out of 2 x 4s and plywood with all the critical clearance measurements. That's what I have done for my new build. Sure is a lot easier building a system on a table, and knowing it will actually clear the shock towers.

Good luck!

 

[yodabiri]

Thats Nice! Do you mind posting a couple of pics of the exhaust manifold?


Thanks!

 

[Anonymous]

drag,

yea it has a straight axle in it and and my bud who owns the car we put the motor in to check for all the clearances and we pulled it back out to build the manifold and once im done with that then the engine will go back in for a final check before it gets puled again for oil lines and proper bolting of the header.


yodabiri,

since i only have friday nights to work on the car i wont be able to get pics of the manifold and i wont be able to put them up till next weekend but i can tell you some info on the header. im using 2 saab 900 inline 4 headers and welding them together and removing 2 cylinders pipes making a one piece 6 cyl header and the turbo flanges will get cut and angled for clearence for the shock tower and so the rear turbo clears the front turbo for intake. i would have built the header out of tubing and a proper header flange but i dont have the money so thats why im using cast iron headers which are actually working out pretty good no problems so far.