ideas on triples, boost at low rpm

I went back to stock on the cyl head. it didnt match what I was doing with the truck so it made performance worse in my case.
I also think a supercharger would cause economy issues.. but I think you can minimize it with the right size pulley, torque converter stall and bypass settings.
 
The towing triples that WOP was building didn't make boost at idle, but they spooled everybit as fast maybe faster than a stock turbocharger would.
 
I know this sounds stupid but,if I were to attempt this project I would use a small set of twins. How I would do it is similar plumbing to the wide open kits. I would run a gt4094 journal bearing my astmosphere charger and run that through the intercooler into a gt2860rs which does not get intercooled but goes right to engine. externally gated of course. the 2860rs is the old disco potato turbo and could probably be had cheap used. i don't how to connect the little turbo to the manifold but i am sure it could be done. way quick spool and theoretically move 85 lbs.
 
sorry 80 lbs. also I would set my gates to run a 2.2 PR on the gt28 and the 4094 at 3.0.I would measure drive before and after the little turbo and keep try to keep the expansion ratio at or below 2.2 which would dictate my PR but hopefully find a happy medium in there somewhere.

as has been said a lot of work for the power potential but hey makes for fun discussion.
 
kawi600 said:
Downside of turbos is the lag - the lack of boost in the low revs.
Click to expand...

What do you consider low revs? I have a 57mm/71mm combo on my 95, and it starts making boost at about 1,500rpm....or are you truly looking for an "off idle" scenario?
 
kawi600 said:
Only worry I have is inlet restriction on the turbo when you put the SC in front.. even with a bypass theres a vacuum.
I know routing the turbo into the SC was tried before, but I wonder if a bypass would work under pressure instead of vacuum in this case.
Click to expand...

We have a vac gauge on the turbo inlet on the latest set-up and it never pulls vacuum, even @ 80psi boost.
We are retro-fitting the older systems to the updated design for those who want to.


SSpeeDEMONSS said:
Like a wastegate set to blow around the.supercharger?

Garrett
Click to expand...

The trick to this is to plumb it so that the blower is not being worked excessively, so it would have to vent to atmosphere or back into the turbo inlet after the turbo lights.

Kaiserbailey said:
Seems like a supercharger would be bad for mileage.
Click to expand...

In our testing, the SC increases MPGs unless an excessive amount of boost is made, where it starts to cost MPGs. With the whipples that has been around 3-5psi @ idle or less is good and higher starts to cost.
$.02
 
Last edited:
Good info, especially regarding boost versus economy
Been thinking.. I may have to fab some sort of dump valve if I go with the supercharger. Cant smoke tailgaters or ricers with all that off idle boost!
 
I think the cam has enough overlap that its hosed my low RPM power / economy. Usually you throw some static compression at the problem and its better. Cant easily do that here so thats part of why im looking at a supercharger.
whats good for power up top isnt usually good for it down low. this is the 'try to have my cake and eat it too' build.
Heh.

Any of you folks with a stock head config measured static compression? Recall what you got? this one measures 390psi on all 6. thought 425 or so was common?
I didnt do a leakdown, but Ill ask the shop about that soon.
 
Last edited:
I got desperate and lowered the timing to 14* to see whats up. It pulls like a champ now and the fueling isnt enough to push it over 1300* so thats good.
Bad thing is without the extra timing making heat, the coolant seldom gets over 150F. Not sure how bad that is for a head gasket if I open it up and its only lukewarm in there.
Money got real tight real quick, so I have to wait on upgrading the turbo.
 
Last edited:
I have no idea.. the shop wouldnt tell me. Just said it was at whatever the old DTT single disc was. I suppose I could test it out.
 
kawi600 said:
I have no idea.. the shop wouldnt tell me. Just said it was at whatever the old DTT single disc was. I suppose I could test it out.
Click to expand...

I run old DTT converters, my 91 in the 98' truck will or would rather, turn the tires over at 1800 rpm power breaking it, that's at say 10 psi on a silver bullet single.

Jim
 
Hurley said:
I'm pretty sure nobody here sees 'measurable' boost at idle with a compound turbo setup.

RonA wins with the logical response-
Click to expand...

It's a tough call to say it's much, but on my 0-100 gauge, boost does not rest on the peg. Also, I've been in unbroken's truck and saw his digital boost gauge read 1psi and I think it was even bouncing to 2 at times.
 
ProCharger maybe? With the right sized pully you should be able to pull some air at idle. And be able to do it without the huge power loss from a conventional style supercharger.
 
05LLYMaxx said:
ProCharger maybe? With the right sized pully you should be able to pull some air at idle. And be able to do it without the huge power loss from a conventional style supercharger.
Click to expand...

Here's a Duramax with a GT4202 and F1R Procharger...spooled like stock, not like a 800-1000rhwp truck....

[ame="http://www.youtube.com/watch?v=D4EcrzWZ1dU"]8000lb Outlaw smokin 2010 - YouTube[/ame]
 
You must log in or register to reply here.
Back
Top