5.73@122.1 DRW/Buick new best.

[Alky V6]

Thats flying on a old school 76. Im not sold on the BW turbos just yet. For going super fast a 47-88 would be the move to make. Or use a 42-76 which would not add much , if any extra spool up time.

I agree with you Louie. I finished tracing out my engine on the compressor map for the GT478818 and if I can match the right turbine housing, the trace line goes straight up, just left of the 77% efficiency island all the way to max turbo shaft rpm and is still at 71% efficiency. I can't imagine another turbo doing any better than that. I did some rough calcs and the .96 looks a tad bit small and the 1.08 a tad bit on the big side. I think I'll go with the .96 to start with. It'll be interesting to see how my nos system does getting this big one spooled. My guess is .8 to 1.0 seconds to get it up to a very efficient 16 psi.

It sure bugs the heck out of me that someone doesn't have a compressor map on the S480 yet. It been out on the market long enough. What are they hiding?

 

[John Wilde]

Don,

Keep up the good work.
On the new turbo would you keep the t4 flange or go to the t5/6?

 

[Alky V6]

Don,

Keep up the good work.
On the new turbo would you keep the t4 flange or go to the t5/6?

Hi John,
Not sure yet. I'm going to get that BP gauge on my present setup and see what's up. If the pressure is up there, my tendency would be to go with the larger flange. What do you think? I know turbine wheel size plays into it too.
I'm presently running a turbonetics Q trim turbine wheel with a .82 a/r housing. I'll let you guys know what BP I come up with.

Would be nice to go with a T4 flange, since I'm already setup for it. The target flywheel hp with the new turbo is going to be around 1,250, plus or minus 10hp. 11.1 hp per lb/min compressor side airflow (thanks to the methanol). This should max out the heads and make them the hp limiting factor.

 

[Alky V6]

I should bring up a point I've discovered with burning methanol. Methanol LOVES compression. With the old engine at 11+ CR and 22 psi boost, it was wicked. If I'd known then to run it richer than I was, I could have put some more boost to it. With this engine at 9.2 to one CR, the fuel is really missing the compression. This engine didn't even start to feel like the old engine until I got it up to 28, 29 psi. Every little bit after 29 psi that I can manage to wring out of this T76 is bringing out the animal in the fuel. When I can start putting more boost to her with a new turbo, it should be very interesting.

 

[Underboost]

That is Awesome Don Wow!! Way to go! So how deep in the 8's do you expect this combination to take you? "Back In Time" :tongue: I hope to see you on 3/22.

 

[Alky V6]

That is Awesome Don Wow!! Way to go! So how deep in the 8's do you expect this combination to take you? "Back In Time" :tongue: I hope to see you on 3/22.

The new setup isn't going to be right away. Still waiting on some information. Some other changes will have to be rear gears and tire size. I'm thinking 3.73 and 29, but probably 30 inch tire.

How deep into the 8s? You wouldn't believe me if I told ya. Hell. I don't even believe me.

 

[Chevota]

Just skip the 8's and shoot for 7's !!

Scott Wile

 

[Alky V6]

That would require a lot more work to the car than I'm prepared to do.

 

[Alky V6]

You know, the more research I do, the more I feel that a T4 turbine housing is going to be too restrictive for a 1,230hp target. Is this the popular concensus with the rest of you?

 

[norbs]

Check your BP numbers 1st and see where your at maybe you can go bigger a/r. Be also interesting to see what your MAt's temps are doing.

 

[Alky V6]

You're right. I keep getting ahead of myself. I've got the laptop out. I'll get the latest IAT numbers for you.

 

[Alky V6]

Here are the latest IAT numbers. These were measured at 18" before the throttle body, in the up pipe. I have no plenum or intake runner numbers.
Boost fluctuating from 305 to 316 kPa.
Start of the run: 95 F. Aftercooler system still warm from a previous run.
End ot the run: 141.8 F. Nice slow ramp up to final temp.
Temp rise: 46.8 F.
The aftercooler is a 1500 cfm liquid intercooler with just over a gallon capacity. I know! I need more water capacity.
How does this compare to some of the typical air/air setups?

 

[Alky V6]

I'll be working on the car this coming week. Just for a primer on my system as it is now.
The setup for the wastegate presently is:
HKS GTII 60mm wastegate.
Advertised adjustable capacity range is 8.5 to 29.9 psi.
The wastegate capacity adjustment is done through different combinations of a supplied spring package (4 or 5 springs) and an adjuster that changes the preload on the selected spring combination picked by the tuner.

Presently I'm using the spring package that is just under the last spring package which is used for the strongest (29.9 psi) settings. The adjuster that preloads the spring package is at half travel. This is where the car did its latest best run. I did try cranking in the adjuster to 3/4 travel and the tires broke loose on the 1-2 shift, so I backed it off to 1/2 travel. I do think that if I can get traction on a run with the adjuster cranked in further, there might be a new best time slip. All this is showing me is that the wastegate is cracked open during the run and I'm loosing exhaust energy that could being going through the turbine housing. So, I don't think I'm at a maximum back pressure number. At least, it's not what it would be if I had the adjuster cranked in more, or switched to the strongest spring package.

Is my logic flawed?

 

[norbs]

Silly, Question is are you putting ice in the tank? Or just cold water? also what was the ambient temp outside? 140 seems not bad for over 30 psi.
You should be looking into a co2 system for you boost control, then you wont need so much spring in the gate. A regualted 50 psi on the top of the gate with a msbc or ams unit would give you precise control between the gears and launching even.

 

[Alky V6]

The water is ambient temp. I don't touch it at all. I just circulate it for a little while in the pits to cool it down.
That's a very good suggestion on the CO2 system. I'm sure that's coming down the pike. At the present level of the car, boost control is perfect as long as I don't try to spin the turbo any further. No boost spike problems and the rise is as fast as I want it. I really don't want to spin it faster anyway. I'm sure it's really close to the suggested safe max shaft speed as it is. I'll be selling this turbo to help pay for the new one, so I want to keep it in one piece. It's been a good little T76.

 

[Alky V6]

An interesting tuning note.
Methanol boils at 149 F at standard atmospheric pressure. The boiling point is higher with higher pressures. To obtain proper vaporization of methanol for proper combustion, I would suggest that it's important to maintain a certain temperature window in the intake, during compression and combustion. The temperature in the cylinder being dependant on factors such as cylinder temperature (engine temp), static CR level, and intake charge boost level and starting temperature. The circumstances of maintaining this temperature window would change with more demanding tuneups, such as the degree of aftercooling and the amount of extra fuel that would be used strictly for the purpose of cooling. The main concern being to keep the fuel away from detonation/pre-ignition limits.
The amount of vaporization that would need to occur in the intake, during the compression stroke and during combustion is still a mystery to me. I'm sure that the vaporization levels at these different stages would be closely tied to the demands of the tuneup (target horsepower).

I don't know how I get into these long hair sessions. Good grief.

 

[John Wilde]

You know, the more research I do, the more I feel that a T4 turbine housing is going to be too restrictive for a 1,230hp target. Is this the popular concensus with the rest of you?

On your new turbo I would do a T6 especially on a alky motor.
Please keep in mind you will need more turbine wheel and housing than a gas motor. With the launch assistance you really have no good reason to retain the T4 flange IMO.

 

[Alky V6]

On your new turbo I would do a T6 especially on a alky motor.
Please keep in mind you will need more turbine wheel and housing than a gas motor. With the launch assistance you really have no good reason to retain the T4 flange IMO.

X2! That is exactly my thinking too. The products of combustion level is higher with an alcohol engine. The T4 housing would just back up easier than it would with gasoline. And the point of the launch assist is well taken. Spoolup time is not a concern with me. It's handled.
I want a housing that is less targeting spool up time and more targeting max hp at max rpm.

 

[Alky V6]

John, what would be your suggestion on the a/r.

 

[John Wilde]

for the GT47 you have two choices (from precision's price list) the .96 and 1.08, I would go with the 1.08 for sure, even bigger if they make one that is not on the list!