Boost EVERYTHING! Challenge Priced New Turbochargers

The More I read Maps The more confused I become........ So my 3.4L has a Garrett with a .60 compresser/.64 turbine.  I really need to make 400 HP or it's not worth it . I think that's about 1 hundred more than I have Now, would 2 of the 48's make that and I need to make that EARLY on in the RPM range . This one is making boost around 3 grand And that doesn't leave a lot of room in the motor to Rev. It's a GM pushrod motor and 7 grand is getting scary, I think  72 hun is about all I want to rev it and I have a Megasquirt to use If Needed.  I need Facts here as Buying another engine isn't Possable, If I do it will be a NorthStar 4.9L and the make 300 HP but at 10.0 to 1 Comp. I am trying to stay light as this is a Challenge car and if it's kinda reliable Maybe a couple Champcar Events. Thanks, John.

I will take one of the high temp t48 if you still have one. where do I send the PayPal?

In reply to FieroReinke :

Shoot me an email so we can confirm details first. Best if you message through the board so I don't have to post my email.

In reply to GTXVette :

Here's the best way I can put it,.anyone else can feel free to chip in or correct me if they see something wrong.

Making some assumptions, this is your engine stock. Makes 185hp with no boost, at 5200 RPM. Volumetric efficiency I stole from a stock VE table for a pushrod 350, which should be similar to any other pushrod GM motor, and thermal efficiency was just fiddled with until it fit the numbers. Close enough, without actual testing.

Now, this is your engine boosted. With no substantial change in engine hardware, richening it up for boost, and changing power output to your goal, this is what you can expect within a margin of error.

So, it looks like 280 g/s (.28kg/s) airflow is going to get you 400hp give or take, at the same 5200 redline, with ~13psi boost. 

That puts you here with a single HP65 compressor map. (Red dot on the compressor map, far right. With an intercooler, go straight up the Y axis.) Not gonna work.

Now, split that flow number in half, to 140g/s, or .14kg/s. This is representing twin turbos. Pressure ratio on Y axis stays the same, since as much pressure is still required to push the extra air in. This point is the blue dot on the below map for an HP48. 

Looks much better, right? In a fairly efficient region at peak power, and the meat of the power band is more efficient. Should mean quick spool and awesome power. Seems like a good fit to me.

In reply to whiskey_business :

I was looking for 550 whp  (647 @ crank?) at 20lbs boost. My P.R. # =2.36 and my lb/min (I converted) was 32.3. The graph converted seemed to indicate the lower end of the efficiency table at 60-65%and eventual  chocking if i added more boost, but my numbers could be seriously off cause it's the first time doing the formula and assuming graph points! 

I see my Dots, red and blue both at 1.9 bar? but the unit I have now is way to the right of the map and the second /Blue dot is in the 70% area of efficiency ,the number at the bottom on the red dot is .28 and the blue dot is 140. could the number difference's just be the decimal point as in 140 /280 or do they represent bigger difference's.

So what would put me in a better range a smaller pair( OF TURBOS) or larger engine , 4.9L caddy (lower comp.pistons than 10.0 to 1) Or would the 4.9 caddy work with the turbo I have now W/lower comp.  or leave the 10 to 1 and let the Mega squirt do it's thing.  I used to work for Cadillac so an engine would cost about the same as two turbo's But Two T's would be less Fab work.. thank you in advance. I do like where this is Going.

And if you have the time what about the 2 T's on the 4.9L . I could Maybe ,sorta, Almost, get this one under Budget.

PS Great Charts I sort of follow that. I once actually Read a Book about this I guess I need to reread it

In reply to 2GRX7 :

Just to clarify, the units on the HP65 map are kg/s. 

Going through the same calculations as for GTXVette, this is stock. More assumptions, but better VE and TE because more modern engine. 295hp at 0 boost. 

Now, adding fuel and increasing desired output to 650hp crank. 

Im getting a pressure ratio of 2, or 14.6psi boost in the manifold, required to make 650hp crank. Numbers make sense to me. As for an airflow rate, 60lb/min or 0.44kg/s will do the trick. Splitting that up across two turbos gives 0.22 kg/s, at a pressure ratio of 2. Puts you here on the map:

Not the most efficient region, but when peak power is right of the efficiency island, that tends to give better response. They will be pushed pretty hard, but won't have any issue making the power. One thing that can help a lot is an intercooler, since it is a slight restriction in the system. Still need the same amount of air, but the pressure ratio at the compressor needs to be higher. It will basically push you straight up on the map, into a more efficient region, and cool your intake air. You trade for a bit of response and sweet, sweet budget dollars.

In reply to GTXVette :

Both dots are at 1.9 Pressure Ratio, this is basically Manifold Pressure divided by atmospheric pressure. So, pressure ratio 1.9 means .9 bar of boost, or like ~13psi. The reason it's the same on both maps is that it requires the same amount of pressure to push that amount of air into the engine. Doesn't matter if it's a supercharger, a turbo, or twin turbos, still need 13psi on a 3.4 like yours. 

As to the units on the bottom, 140 is grams/second, and .28 is kilograms/second, so just a decimals thing. .14 kg/s is the same as 140 g/s. 

Breaking down your questions:

• If your current turbo is tapped out at 300hp, putting it on a bigger engine won't help. Horsepower needs airflow, and if your turbo has no more airflow to give, then it won't help a bigger engine.
• Look at the response I left 2GRX7 about his 4.8 LS, that's awfully close to what a 4.9 Northstar would look like with two HP65 turbos. 650hp is possible.
• Northstar with 2 HP48s will be a torque monster, but will choke out at ~450hp.
• Don't know how strong the bottom end on a Fiero is, but keep in mind that you're gonna double the abuse on it with 400hp. 

Lot of different ways you could go. 

hmm.

4.6 mod motor npi... For... reasons. 

sounds like a singe HP65 would boost it right?  (i'ts the 215 hp 1996 version with crappy everything internals so 400 hp would be ideal..)

edit: after re reading your response to GTX it looks like I'd be just barely on the table with the 4.6.  (similar power but 1.2 liters more motor).  so two 48's would be better.  Too much for challenge budget though. 

In reply to whiskey_business :

Yes, my numbers were relatively close to yours (i used a youtube video and  converted Kg/s to lb/min as the video used lb/min). I ended up in the 65% efficency range, which had me concerned for more PSI down the road. An intercooler will be used in my application. Thanks for the verification! PM'ed you!

In reply to Mad_Ratel :

Just one HP65 might be a bit small for that kind of motor and power. PM me, we might be able to work something out.

In reply to 2GRX7 :

As long as it stays west of the choke line, it shouldn't have too negative of an effect, especially with intercooling. Remember, how long are you at peak power for autocross? Even drag racing? 

PM Sent,  enjoy the read. Yes I'm serious and mostly Sane. 

In reply to GTXVette :

another Pm sent

In reply to GTXVette :

Replying now.

Your Too Cool,  Thank you !!!!!!!!

Yes he is, great to be able to get this level of advise on these turbos, can't wait to spool mine up!

If the birthday in his Contact Info is real then his Knowledge at his age is Something, At 22 I was still at H-D  U, School of Knuckleheads.     But Once I Learned My  Goesinto's I went to Airplane (A&P) school.

I have a lot of people smarter than me to thank for what I know about engines and turbochargers. 

And That Is Why,    When The Great-Grand Kids Say Why,    I answer them.

Any of the HP48 or High Temp HP48s left?

Lots of HP48, the last High-Temp one went in the mail last week. 

Have anything that would be suitable for an 7.8:1 compression 2.2 Turbo 12v with good spool?  Or a DOHC 3S-GTE MR2 Turbo?  Prefer something with a V-band downpipe.  Any T3 flanged t3/t4 comparable units?

In reply to dansxr2 :

The HP65s are very similar in performance to a T3 Super 60, and I can grab you one of the tighter exhaust housing ones to get better spool.

In reply to whiskey_business :

Shoot me an email. I tried to send you a PM via the GRM Forum, but it came back returned.   DansXR2 at Yahoo dot com.