I just got my car back ~ 500 miles ago from RT tuning after a Greddy twin turbo install. My car has 120K and the 2003 VQ35DE was bone stock.

Parts installed:
Greddy 18G TT kit w/FMIC
NGK LFR6AIX-11 1 step colder Iridium spark plugs
R35 570cc GTR injectors
Walbro 255 fuel pump
TiAL Q BOV
Greddy Profec Type S boost controller
Defi boost gauge/prosport wideband
UpRev w/MAFGT
Motordyne 5/16" plenum spacer

Low boost 7 psi made 384hp/367tq
High boost 10 psi made 406/392tq

I love it so far! boost is definitely a different world! I especially love that RT tuning got the tune really good that the car feels like stock out of boost and boost comes on really smooth. It is a lot of fun! I am still getting used to the new power so I haven't been able to get on it as much.

Here is my dyno sheet - Vince said that he pulled the timing back a bit at the top since it's a high mileage motor, he said this was a pretty conservative tune.



Here is my dyno video

 

did you do a compression test before your build? Might be a better indication of your engine health than your odometer?

great numbers though and enjoy the rig!

 

I can tell he tuned it pretty conservatively... I'm making 443 whp @ 8.5psi on a 132k mi engine with a worn out greddy 18G kit with modest timing. Word of advice -- watch the oil level carefully, like checking it at every fill up.

 

Yeah I remember looking at your build prior to getting mine installed I wanted your numbers but I'm still happy with a conservative tune. They put motul 8100 5-40 I'll check it at 1000 miles. What oil are you using?

 

No I didn't because it was a few hundred more to get the test done so I opted out. Figured I could just put those few hundred towards a built motor if this one ever blows lol. Hopefully not anytime soon though. I am enjoying it so far it's a lot of fun!

 

I also wanted to ask you boosted guys about the blow off valve, I know it's temporarily rich because of the maf sensor and it's dumping more fuel in while the air is coming out of the bov. So what do you guys do about it? Recirculate or just leave it as it is?

 

On the greddy kit the BOV is pre-MAF so it's seeing the correct airflow even when the valve is open. It's pretty common to go rich for a second or two when letting off the throttle though, all my VQ's have done that, it's mainly due to tuning limitations of the stock ECM and not a bad thing either when you're boosting an engine that was never designed to see boost.

Also my higher numbers are mostly attributed to the exhaust system... 3" downpipes and true dual 3" exhaust, so literally zero backpressure. Greddy's and most turbo setups in general hate any amount of backpressure.

With OEM cats instead of 3" downpipes the same setup made 380whp, and with the OEM exhaust it barely made 350whp. So... 350whp -> 443whp in the exhaust setup and just a touch of timing.

 

Who makes your downpipes? i have the stock downpipes going into CNT high flow cats (that's because it is so hard to pass inspection in NJ I finally gave in to putting cats in after having test pipes so long. and then I have a JIC Y pipe and Fujitsubo exhaust which is a 3" exhaust but it's not a true dual exhaust like yours.

What type of oil do you use?

I ended up going with UpRev over UTEC and it's pretty smooth in and out of boost. I am very happy with the tune in that sense.

 

Congrats!! Welcome to the world of boost and fun.. it's addicting as hell. I hope your block holds up w the mileage.


And couple hundred for compression test? Holy cow, you can do that yourself. A shop here charges 160. I diy-ed it.

 

i have 116k on mine will throw up numbers Friday

 

call me crazy...

If your block blows, you will lose a ~$1500 core deposit as your block will be scrap at that point.

$300 < $1500

Keep it in the back of your head...maybe not today or tomorrow, but have it done next time your car is in the shop.

 

Yeah but to think about it, I could just do it myself. If there is low compression in one cylinder or two, I would still have to rebuild the block. I don't see a difference in the outcome as much.

I'll do a compression test if any problems arise

 

They are made by AAM back in the day, probably would have to be made to order at this point, I'm not seeing them on their site any more. But the good news is the greddy kit uses standard downpipes so your typical 2.5" ebay test pipes or even stock cats could be used as a jig. Getting harder to find stuff these days for DE greddy's... like the upgraded oil return lines which I need pretty badly.

For oil I use M1 0w40 in all my stock block boosted VQ's.

Uprev is good (I use it on my boosted G35) but for my tired Z I feel better with the added protections of the UTEC (static timing, map tuning, overboost cut, agressive knock retard) especially on such a powerful kit. Drivability in and out of boost is surprisingly good. But I'm cheating with 440cc injectors, UTEC gets pissy with anything bigger and fortunately I'm below 80% IDC due to the fuel return and relatively high base pressure.

 

550cc here on UTEC. No problems. Though my rev-limited option doesn't work

 

Ya, utec only supports up to 600 cc injectors, is thst corrret??

 

by supports, that just means that the 0% tuning column cant pull enough fuel out under vacuum to achieve a 13-14:1 AFR.

If you dont mind running rich under vacuum, you can run 800cc's
Or flash the ECU with uprev and run any size injector you want along with the UTECs safety features and ease of tuning.

 

I still have the utec available. Do you know of anyone running both utec and uprev? I asked and they said it might conflict. If you had uprev would you sell or keep the utec ?

 

Even 440's have issues even though you might not know it -- UTEC's method of 'scaling' is by pulling down the MAF voltage. This causes the ECM to add timing (to the point of pinging), retard the cams, and work towards the wrong A/F target since the load scale is now off. It gets worse with larger injectors since you're pulling more MAF voltage to compensate. IMO the only way to get the vacuum timing/fueling proper is to scale and tune vacuum with Uprev with the 0% column set to 0, and do the boost tuning on the UTEC. After spending all the money/time on two tunes / ECU's you might as well had bought a standalone .

 

Thanks for thr good info clearing some things up guys.. Haltech it is huh?