Guys, have somewhat of an engineering question for you. I had been in talks with Performance Factory to get Greddy twins, but unfortunately it fell through because the "Roger Clinton" in my family needed my wallet.

So it looks like I'm stuck with my defective Vortech. Once (or if!) it's fixed again, I'm looking for an affordable, safe way to get close to 400 hp/350 ft-lbs at the wheels. I'm currently pushing 364/313.

My defective vortech buddy G35Asian found some interesting information though, us non-revup guys may be limited to the 3.12" pulley or else the impeller may spin too quickly (maybe this wasn't a concern once upon a time, but with the bearing issues recently, I don't want to take any chances). So I may be limited to bolt-ons, ignition upgrades, and a retune. I'm thinking of getting bigger injectors (current running 440cc's), an HKS DLI II, and Borla cat-back. Do you think that a precise retune, purposely making the A/F ratio rich (via scaling 550cc injectors or bigger), plus the DLI II to burn the richer mixture, and the Borla adding a little gas throughput will achieve the goal, or come close to it? I have a feeling the answer is no, but I'm hoping I'm wrong!

 

IMO if the bearing issue is so severe, it wouldn't matter if you had the 3.33 pulley, you're going to wear the bearings if they're defective to begin with.

The 2.87 works just fine. Lots of people run it with no problems - given they have good bearings to start with. It will wear them out faster though. According to vortech, the 2.87 pulley really shouldn't be taken past 6400 rpms, but I honestly think it's fine to go an extra 200 rpms anyway. It's not like you're spending large amounts of time going beyond vortech's claimed limit

you can gain power with bolt-ons and a good tune. I think 400whp is totally possible with the right parts, but not 350tq. To get to 350 tq would involve getting the 2.87 pulley. You have to realize that if you hit 350tq would most likely mean hitting 440whp if your belt isn't slipping at redline

 

I agree with Sentry on the TQ... I do not think 350TQ is real possible with 3.12 on a non rev....

I have the 3.12 on my 04 and am right at 400 - 405 rwhp / 330ish tq (I got to find my dyno again) and am doing it at 9.5psi on stock rev limits.

I did lose roughly 10tq with the SSV however from the crawford... looking forward to what the cosworth can do.

 

merry xmas everyone!

yeah, actually, looking at the numbers of 364whp/313 tq - something is up. You should be hitting around 390whp with 313 tq at 6600 rpms. I'd guess it looks like your torque curve goes up and hits 313 tq then starts dropping a little as it approaches redline? To reach 364whp at around redline would mean your tq is something around 290 at around redline. So somehow you're losing 20 tq

it could be the belt slipping or a tuning issue or possibly your exhaust is too restrictive maybe? Just a thought anyway. I'm not sure what your exact setup is

 

The OP is making good power at the 364whp and 313rtq. stated . He has a AT5 tranny , if you took the time to read his sig . Thats probably DynoJet numbers also . I made 350whp on a Mustang dyno with a host of aftermarket breathing and other mods . To get to 400whp , he will need the 2.87 pulley , a bunch of other mods , and a high reading dynojet dyno .

 

How about a small shot of nitrous?

 

Well, the great part is that I already have the 2.87 pulley, just scared to put it on!

Yeah, the numbers are a result of the auto & dynojet. I've got that nasty ~20% drivetrain loss!

Thanks for all of the feedback guys. It sounds like whatever we do, we always take a massive hit on the torque from the parasitic loss. I was preparing myself for 400/400 with twins at ~7.5-8 psi.

So sentry, based on your Vortech bible, the 2.87 pulley is good for about 35 whp? Assuming the hp/torque increase is proportional to my current gains over stock, hopefully it will add 24 ft-lbs at the wheels? With the 2.87 pulley, bigger injectors, borla, and retune, maybe I can pull 400/350 or close (although I've read some nasty stories about borlas robbing people of torque). I guess I'll just have to be careful to avoid 6400-6600 RPM like you said. I've switched over to tiptronic mode most the time anyways now, so that should be easily controlled.

Merry Christmas!

 

I thought about it, especially after reading Jeremy's post about the vortech + nitrous setup PF tested. I don't know though, to be honest, I kind of like having the torque similar to stock down low. So easy to gain traction, then it swoops in and there's no slippage. I'm really looking for a combo of great power/torque in the midrange and above, traction, and stability.

 

I think you'd hit your goals with no problem with the 2.87 pulley. I wouldn't take it lightly though and just throw it on or anything. You gotta do things right and make sure you have all the right supporting mods for it like larger injectors, walbro, possibly return fuel system etc. But usually everyone who does those things has run the 2.87 with no real problems

the borla is a decent choice, but some people might be turned off of it by it only being 2.25 inch diameter and being so many pieces. I had one before a long time ago and it wasn't too bad. It loses tq because it's mainly optimized for upper rpms. It's really designed for NA use really, but depending on what other breathing mods you ultimately end up with, it can run just fine with a vortech setup

 

Like I said . If he found a high reading DynoJet....like maybe the one in Socal that some guys drive hundreds of miles to use...lol He can hit 400whp

A 2.25 in. dual exhaust is going to flow better than a 2.5 inch exhaust choked up by cats , High flow or not . I never heard of an exhaust that loses trq down low and be a good N/A at the same time .

The trq loss down low by openning up your exhaust with headers and test pipes is very minimal compared to the hp gained up top . Ive gone from stock cats , RT cats, test pipes , back to Crawford cats , then back to test pipes all on the Stillen dual 2.25 in. exhaust . The power gained up top , far out wt's the trq loss down low by far running no cats . I would tend to think running a 2.5 or 3 inch dual exhaust with HFC's . Would lose just as much trq down low . Some people tend to over think things and love doing the ricer math thing .

 

I have the borla and I don't feel a lost of tq down low. The only bad thing is the million of pieces it comes in but if u get the main pieces welded then there's no way it should cause lost of hp/tq. Also, if I remember correctly there was an old post on my350z.com that had an exhaust throw down and borla came out on top. And not to mention there's no drowning sound like most exhaust (HKS, injen, etc) when you drive on the freeway... best of both worlds.

I have to also agree with booger on this that running a 2.5+" dual exhaust would lose more tq down low compare to the 2.25 piping.

 

Thanks man. I think my framework is good for the upgrade, I probably just need bigger injectors and a retune (already have a walbro, UTEC w/MAP sensor, 440cc injectors, NGK one step colder, Crawford HFCs, and a 5/16 spacer). I'm trying to avoid the fuel return system though, so I guess it comes down to a choice between 550cc and 650cc injectors.

My borla concern may just be beating a dead horse - I was worried because a while back someone posted that they had lost 10 ft-lbs or something in that range (which I guess for all we know could have been a bad dyno run). You guys are right though, in the FI power/torque ranges, we can't be talking about a significant loss - or if there is, hey, more traction before that boost kicks in! The borla is just a perk I want to throw in anyway, been a borla fanboy for years.