Almost any turbo will make 20 psi. The question is, will they make 20 psi efficiently? This is where compressor maps come in.

Mark

 

That's where I run into some sort of mental block. i look at a compressor map and all I see is a test I failed in the 8th grade.

If someone wants to break it down shotgun style for me, I'm all ears. (well, eyes anyway.)

 

Figure out your pressure ratio. Find that number up the side. Draw a line straight across.

PR = (boost + 14.7) / 14.7

(note that 14.7 or 14.5 could be used)

Figure out your airflow. Basically, divide your desired horsepower by 10, and find that number across the bottom. Draw a line straight up.

See where the two intersect, and see which "efficiency island" the intersection falls in.

Mark

 

I did a quick scan of Google and can't find a compressor map for the turbo i'm running to save my lfe...

 

Neither can I...just take your inducer and exducer dimensions and try to find a compressor wheel that's close.

Mark

 

OK, here's what I've found so far.

It's labeled "TO4E 60 Trim." Unfortunately, no actual info on the turbo itself is matched up with this map.

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Now, do I understand it correctly in thinking the closer you are to the middle of the 'distorted bullseye", the greater the efficiency of the turbo?

If that's the case, this one runs out of steam at about 30 pounds, which is roughly 2x atmospheric pressure?

 

Go back to what I posted...did you figure out how much power you want to make?

Mark

 

You're going to laugh, but I never even SAW that post. I opened up a reply post page and was looking for the compressor map. When I hit "post" you slipped your post right in between my two.



What I come up with is 2.36 and 85. (I'm guessing at 20#, though.) Also, since I'm running a twin kit, do I simply half the HP number?

That'd put me at 2.36 and 42.5.

It appears to be withing the 74%-75% range. (If I'm reading this right.)

Am I getting this?

 

Yup, cut the flow rate in half if you're running twins (to get the flow rate per turbo), but the pressure ratio stays the same. You're getting it! You seem to be in a good efficiency for that boost and power level.

Mark

 

short bus is right. with that pressure ratio and your engine size, you shoube right at 850 flywheel hp. you should be able to pull off right at about 725 flywheel hp on pump gas. That puts you at 15 psi. should be haulin ace anyway..lol

 

I'm looking to make 850 on pump gas.

I'm hoping the Meth Kit helps me get there.

Here's the fastest way to give you guys an overview of the car:
http://www.gotstang.com/profile.php?Big Top Gt

Assuming it works, it's got a complete rundown on the car.

 

Oh i didnt know you were running meth. 850 is definately possible on meth @ 20 lbs. Should run like a raped ape.

 

Were did you get the spark plug covers?

 

I think you can get them from UPR for like 40 bucks. I'll see if I can get you a link.

 

Here you go:
http://www.uprproducts.com/shopping/shopexd.asp?id=283

45 bucks plus shipping.

 

Coming back to the B Heads

Do you use the stock valve seats? Up to how much boost/hp?
I have one dropedone exhaust seat in a cylinder with a KB on a stock Cobra, but may be this was problem with detonation and a melting exhaust valve.

Udo

 

Keep in mind that that map is for fwhp. If you are looking to make 850rwhp, you need to add 15% for a manual and 20% for an auto. So you'll be pushed out a little further.

 

Why is there a 15-20% difference between front wheel horsepower and rear wheel horsepower?

Mark

(anyone who knows me knows that I'm dicking around lol)

 

LOL.