Surge on the top end

CR From Hell

CR From Hell

Never Satisfied
Didn't make it to the track last night, so I thought I would do some keyboard racing. I swapped to a .90 housing from a 1.0 in an attempt to minimize/end the surge I experience at the top end of the track. I know that surge is hard on bearings, lord knows I don't need to lose another turbo, but my question is does surge effect ET/power while going down the track? In my head I was thinking if I could get rid of the surge, thus keeping constant/more airflow and pressure going to the motor shouldn't I be able to make more power and run faster? My best time thus far is 11.8@116.

Turbo is currently a box BW 475/83/.90 (now) and the setup is as follows:

110# Hamilton Valvesrpings
Extreme Duty Hamilton Pushrods
ARP 625 Head Studs
100% Exergy's
Dual Stock CP3's
FASS Titanium 200
Stainless T4 Manifold
Smarty TNT-R
Caltrac's
QA1s in the rear
Front/Rear Driveshaft Loops
Goerend Tranny (built by Ashley Black)
 
nwpadmax said:
What boost are you at when the surge happens?
Click to expand...

Usually ~50 PSI. Once it hits overdrive it surges until about 2300-2400 RMPs. The boost gauge jumps from 40-50 PSI until that point.

Smokem said:
Need to loosen turbine AR or go to a smaller inducer if you want to get rid of the surge.
Click to expand...

I swapped to the .90 and did a few WOT runs this weekend. Had the boost gauge pegged at 50 PSI and didn't surge a bit that I could tell. But to me that would be "tightening turbine AR". So if I started with a 1.0 AR and it surged by "loosen turbine AR" should I be looking for a 1.10 AR? If you don't mind please explain why that will help, I'm trying to learn as much as possible. And smaller inducer like a S471 or S472mm, or smaller than that like a FMW 467? Thanks!
 
DieselheaD said:
I blame it on the extreme duty pushrods and drive shaft loops...

are you running a stock intercooler?
Click to expand...

:hehe: Gotta be those darn driveshaft loops? And yes it's a stock intercooler from an '06.

JQmile said:
What are your shift points? Can you rev it higher?
Click to expand...

To be honest I don't know the exact shift points, I know when I race I have the shift limiter off on the Smarty. I believe 1-2 & 2-3 are right around 4,000 RPM, it's the 3-4 that gets me, wanna say it drops to around ~2,300 RPM. Then it takes me about a second to get back on top of the charger. I'll set up my Go Pro this Friday to watch the tach and any other information y'all need.
 
I could be wrong but the % ratio changes from 2-3 and 3-4 in a 48Re are about the same, so if it only does it on the 3-4, maybe it's shift point related. Plus whatever converter lock strategy there is would come into it as well.
 
I had thought it could be shift related as well, just wasn't sure? I'll see if I can get more information on the shift points, and I know that the convertor locks in second then pulls like crazy til the end.
 
whoops...nevermind

45% drops would happen in both gears, so at 4000 you would drop to ~2200 in both cases.
 
Last edited:
I'm definitely not up to speed on the percentages, but that sounds about right. I'll be sure to pay more attention and get it on film.
 
You must log in or register to reply here.
Back
Top