lcvette

Hey guys,

sorry it took so long, here is the dyno graph for the run, this was the 3rd run I made, the 4th was 939/896, but I sent myself the wrong one from home so here is one too look at for the time being.

Enjoy!

SurfnSun

I wanted a side by side comparo of the smaller turbo.

I think I like the torque curve of the smaller turbo a little better for a more fun street car...knowing the bigger turbo will ultimately end up the faster car. That thing will kill it in the 1 mile.

Thoughts?

dustmann

I like it!!!

93 ragtop

Hey Chris,

Did you ever get the bigger injectors?

lcvette

Hey guys,

93 ragtop,
Yes the 160's are in, that was the reason for not being able to really turn it up to much at the dyno day, was trying more to trim the fuel to where it needed to be.

Dustmann,
Thanks, I do too...

Surfnsun,
Make no mistakes, you may think you want the insta torque and it is fun for a while but it his sooo hard in the lower rpms that the car never has a chance to try and catch traction. and also that turbo as you can see is spent in the upper RPMs, this new turbo has a different feel to it all together mu more subtle on the onset but ramps up very nicely it feels different mainly because it is a little laggier which is fine for me since I like the top end better then the torque but the other turbo hit like a sledgehammer down low it just petered out up top.. a nice compromise would be something with a newer more efficient wheel on the turbine side and a little bit smaller compressor wheel with a better trim ratio, the PT88 has such a smaller exducer on the compressor wheel that it handivcaps its full potential as an 88mm turbo.

I am sure it won't be too too long before on of these companies bridges the gap but until then I think I prefer the top end rush of the 88, especially since I plan to go single plane intake and a bigger cam in the future which will extend the RPM range and require the extra airflow.

Chris

SurfnSun

I know you were having a lack of fuel issue but in my world 700rwhp isn't "petering out" Ive never driven anything that powerful, I can only imagine. Have you considered a variable boost controller?

I can totally see where the slightly more laggy turbo would make for a better 1/4 car...much like the big single Supra. 7krpm with a single plane?

"swamp rat"

MY only question is What C.I. Do you have??????

lcvette

a little old 355cid stock stroke, small block

Chris

93 ragtop

Hey Chris,

One other question if you dont mind. I thought on the E85 the AF mixture was around 9 or 10 to 1. That dyno sheet looks more like 12 to one. Am I missing something here? Thanks for the education!!

lcvette

9-10:1 AFR on E85 shows as around 12-12.5:1 on a "oxygen sensor" plot. most oxygen sensors and loggers such as the default logging tool in DFI read Gasoline only so the data it receives from the O2 sensor is in percentage of oxygen left over in the exhaust. because there is more ethanol added to reach stoich, it does not require as much past extra fuel past stoich to achieve a desired power AF ratio.

If I switched my logger to read lambda it would be different, some loggers have a switch inside them to use on flex fuel or ethanol or methanol etc.

so to answer, the AFR is still a little fat on mine and I may lean it out some once I get the boost settings where I want them.

Chris

mnstrlt1

Chris-

I noticed that you modifed the radiator shroud and associated components. At this point, do you believe that two turbos could just as easily be placed over the "cross-frame", since the shroud will be modifed and the radiator moved-replaced?

Seems as though a "correctly" sized set of turbos would make good power with a wider power band (i.e. insane top-end, with acceptable "low" and mid-range). as compared to a massive single... of course more cubic inches will also "aid" the bottom end-street friendly issue.

lcvette

it is a misconception that twin turbos spool faster when sized to make the same power as a single, a smaller aingle and two smaller twin rated at the ame horsepower level will have similar spool.

the "insane top end" will only come from two much larger turbos which again will create a good deal more lag.

Chris

"swamp rat"

OK! I Building one now to run Nitrous !

mnstrlt1

thanks for the clarification, I guess that would explain why mazda and toyota when with tubo's in a sequence.

What are your thoughts of porsche's variable-vain turbo?

lcvette

there are several options out there.. in my opinion until the technology is out for the aftermarket, it is just too expensive to try and fix something that is not really that far from being perfect.

Chris

mn_vette

Nice numbers Chris

So did you win the Domestic/Import shoot out?


So how much extra power do you think that E85 is giving you?

5abivt

those #s are