Out of curiousity why does everyone use 2.5" on the crossover pipe
02-02-2014, 12:22 PM
#301
stock ls1
stock 799 heads
7000 rpms
7-8 psi
methanol
10.5:1
im getting to the point where im not sure ia loose converter is a bad thing on some low power combos like we see around here <800hp. the jury is still out on that one.i know the na guys have a saying loose is fast. im still testing how that applies to low power turbo combos
so you think it will work because of a loose converter? but with a tight converter it has no chance??? is that what i hear you saying?
stock 799 heads
7000 rpms
7-8 psi
methanol
10.5:1
im getting to the point where im not sure ia loose converter is a bad thing on some low power combos like we see around here <800hp. the jury is still out on that one.i know the na guys have a saying loose is fast. im still testing how that applies to low power turbo combos
so you think it will work because of a loose converter? but with a tight converter it has no chance??? is that what i hear you saying?
1 7/8" headers have made 2600-2900hp
3" mid/crossover pipe have made 3000-3200hp
And your talking about making 550hp at the tires.
With that being said methanol/compression will give you a margin of error on the pipe size and still be able to spool a reasonable converter but your still going to end up with excessive slip on the big end.
We are not building a NA combo, turbos like load.
02-02-2014, 12:32 PM
#302
I will plot the numbers tomorrow but it just looks off in right field.
1 7/8" headers have made 2600-2900hp
3" mid/crossover pipe have made 3000-3200hp
And your talking about making 550hp at the tires.
With that being said methanol/compression will give you a margin of error on the pipe size and still be able to spool a reasonable converter but your still going to end up with excessive slip on the big end.
We are not building a NA combo, turbos like load.
1 7/8" headers have made 2600-2900hp
3" mid/crossover pipe have made 3000-3200hp
And your talking about making 550hp at the tires.
With that being said methanol/compression will give you a margin of error on the pipe size and still be able to spool a reasonable converter but your still going to end up with excessive slip on the big end.
We are not building a NA combo, turbos like load.
testing will be in a month or less. my theory is that it will make boost quicker than it can be used and that there will be no greater backpressure than boost pressure.
this is all theory though. testing will prove if it works or not.
02-02-2014, 12:44 PM
#303
I think by your calculations,iirc, 550whp should need like a 1.75" crossover? which would be less than the size of one primary pipe?
testing will be in a month or less. my theory is that it will make boost quicker than it can be used and that there will be no greater backpressure than boost pressure.
this is all theory though. testing will prove if it works or not.
testing will be in a month or less. my theory is that it will make boost quicker than it can be used and that there will be no greater backpressure than boost pressure.
this is all theory though. testing will prove if it works or not.
My gut says 1 5/8" headers and 2" crossover on methanol.
02-02-2014, 01:47 PM
#306
I was running a 9.5" vigilante "0" pump (~2800 advertised) and it worked ok but was flashing to about 5000 (shift at 6200) at full boost but was too tight on the brake to spool. I swapped it out for a vigilante "turbo converter" that was supposed to be looser at low rpm/load which would help spool. That thing was SLOPPY loose and was flashing to 6000 on a whim. The car would barely go over 100 mph! I even data logged it and sent it to precision. They wound up sending me a 10.5" for increased holding power. The combination of a heavy car, high torque output, and low rpm limit meant I couldn't tolerate much slippage. The 10.5" worked very well, as it would slip enough on the brake to build boost, and yet only flash to about 4400 at full boost. The car pulled 146 mph with that one on a 26" tire and 3.00 gear.
02-02-2014, 06:02 PM
#307
IMO an excessively loose converter is a crutch for a car that can't get out of the hole. Which makes sense considering the ET gained by improving your 60'. But if you can have a tight converter and still launch the car just as hard, how is that not a "win win" situation? You won't have both without the combination sized correctly as a whole. Racing is about making the most efficient use of power. Nothing efficient about a 15-20% slippage loss.
02-03-2014, 09:40 AM
#312
stock ls1
stock 799 heads
7000 rpms
7-8 psi
methanol
10.5:1
im getting to the point where im not sure ia loose converter is a bad thing on some low power combos like we see around here <800hp. the jury is still out on that one.i know the na guys have a saying loose is fast. im still testing how that applies to low power turbo combos
so you think it will work because of a loose converter? but with a tight converter it has no chance??? is that what i hear you saying?
stock 799 heads
7000 rpms
7-8 psi
methanol
10.5:1
im getting to the point where im not sure ia loose converter is a bad thing on some low power combos like we see around here <800hp. the jury is still out on that one.i know the na guys have a saying loose is fast. im still testing how that applies to low power turbo combos
so you think it will work because of a loose converter? but with a tight converter it has no chance??? is that what i hear you saying?
02-03-2014, 10:05 AM
#314
IMO an excessively loose converter is a crutch for a car that can't get out of the hole. Which makes sense considering the ET gained by improving your 60'. But if you can have a tight converter and still launch the car just as hard, how is that not a "win win" situation? You won't have both without the combination sized correctly as a whole. Racing is about making the most efficient use of power. Nothing efficient about a 15-20% slippage loss.
Once you do most of the big stuff correctly, you can fine tune it with cam timing, fuel, ignition timing. It spooled slowly before we started tweaking the 3 fine tuning things and it came around very fast.
Most people miss the combo by a few items and it plays havoc on spooling so they have to get a loser converter to get it up onto boost.
I can tell you this, Marty Chance gave me the tightest converter and it still needed to be tightened with a custom billet stator. At that time I didn't want to put more money into the converter and got a deal from ATI.
02-03-2014, 10:59 AM
#315
put your "extremely tight" blown alcohol converter in an 800hp combo and tell me that it will be the quickest down the track vs the right converter.
you guys with your hard and fast rules. and No, I dont have any turbo experience lol
02-03-2014, 11:47 AM
#316
lol. I think the same can and should be said about you.
put your "extremely tight" blown alcohol converter in an 800hp combo and tell me that it will be the quickest down the track vs the right converter.
you guys with your hard and fast rules. and No, I dont have any turbo experience lol
put your "extremely tight" blown alcohol converter in an 800hp combo and tell me that it will be the quickest down the track vs the right converter.
you guys with your hard and fast rules. and No, I dont have any turbo experience lol
1st off you wouldn't put a blown alcohol converter behind a 388" small block genius. You would put the right converter and yes its going to be a nitrous/blower converter. Turbos LOVE LOAD BUT you wouldn't know that because...... You don't have any experience.
02-03-2014, 05:11 PM
#319
388"
1 3/4" stepped to 1 5/8"
2 1/8" Crossover
2.5" merge
388"
10.5:1 CR
7500rpms
Q16 or C16
25-28# of boost if it will make it
~1500hp
On methanol I would step up the crossover to 2.25 and the merge to 2.75
02-03-2014, 09:31 PM
#320
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I just spent the last couple hours reading this entire thread and as well as the one on YB's TOBT. I'm glad I did as I'm starting to build another hot side for a new project in short order.
I have a couple questions.
Sometime ago I read where its beneficial to merge several inches prior to the inlet flange. Does this still hold true?
At the flange, assuming a t4, are you simply forming the 2.5" merge to the inner walls of the flange?
Thanks
I have a couple questions.
Sometime ago I read where its beneficial to merge several inches prior to the inlet flange. Does this still hold true?
At the flange, assuming a t4, are you simply forming the 2.5" merge to the inner walls of the flange?
Thanks