Just upgraded from a GT35R to a GT40R...just need to know if I need to retune the car after the upgrade...it was tuned to 11.2 read on the UEGO guage with the 35R. Kinda rich, should this be good for the 40R...maybe less since the turbo is larger? I am not a guru obviously but any advice would be great!

 

If you are switching turbos, you should really re tune altogether. Just to be safe, ya know?

 

That's what I was thinkin...just that I stepped on it a couple of times and it stabs pretty hard...but then again that was low rpm, never over 7k. Guess I'll hit the dyno this weekend...any suggested tuners in the SoCal area?

 

it will spool different, you need to adjust the timing and fuel

 

Since the 40R flows more then the 35R, you will blow your engine up if you do not retune because its going to run lean.

thewird

 

Yup, I'd definitely get a retune. I'll be curious to see if you like the 40R better, what kind of boost levels are you running?

 

I bet you will not see much better results unless you really push it. I remember Ray making 600+rwhp on members old car but I wonder how far a 35r would have went???

 

if you ever do any tuning on your own you will realize just how little it takes to throw off a tune. I switched from BUR9EQ plugs in the leading to BR10EIX and I had to redo the whole ignition and fuel on my car with Power FC (big streetport, 720 primary's)

 

Running 13lbs right now, but getting a worldpac boost controller. I hopefully will push it to 20lbs on the retune. It seems like the 40R spools just as fast if not faster than the 35R, but I haven't gotten to really step on it since I should retune first. Thanks for all the info rotorheads!

 

Hm, from what I've read over the years going from a t4 35R to a 40R will yield more lag and not much more power at that boost level. Keep us updated......

 

I definately reached the limit of my 35r.. not sure how much better a t4 would have done. What car made 600 with a 40r?

 

I bet you it "feels" better because it is running dangerously lean making it more responsive.

 

mr2foryou


604 at 28psi. tuned by ray wilson.

 

Yeah, you're probably right. I'm hopefully takin it to the dyno next week sometime when I get some suspension parts installed. The only reason I even upgraded is because my 35R started whining (sounding like it's goin bad) and I got a sweet deal on a 40R from a friend. My 35R was a Precision...the 40R is a genuine Garret. I'll keep all posted on the results...