Hey guy's I'm still researching what turbo to get and came across this app from Garrett called Boost Adviser... I inputed some stats Ie. Location, 3.8l, 2V, Peak power RPM, Intercooler design etc... Anyway It showed me recomended turbo's and theyre all pretty huge IMO.. Ranging from 76mm-94mm... Im building a 3800 l67, I put a ST3 Camshaft in, I decided on a Water to Air. And I want a good drivable DD Turbo with the ability to ramp up the boost to get 600 BHP. I'm running a beefed up 4t65-HD, and will put in a 3250 stall?.... From what I've been reading, I was thinking 66mm, but now I'm not to sure... any input? And for the record, I would like to get one 10sec pass out of it, but in the end it will be a weekend car... I'd be okay with using cheater spray to get that pass. (No holset turbo's) thanks!!!
to get a 10 second pass in a Fiero you don't need 600 hp. 500 will do the job.
the larger turbo, as you likely know, doesn't spool up as fast but makes more at the top end. If you are asking the app for maximums, it will give you the top end, not driveability.
The one guy on the forum who likely knows is PBJ. I'd send him a PM.
3250 rpm stall, what's your gearing like considering you intend for this to be a daily driver. I personally wouldn't go higher than 2000 rpm stall for a daily driver. With a high stall automatic you should be fine with what they're recommending as the stall counters the lag. Just make sure you compare your intended daily driving habits with the nature of your drive train nature. I run a T67 with 4.2 litres and initially a .81 turbine housing but my driving habits favor quick acceleration so I went down to a .68 housing which spools quicker and is a bit more fun. On the interstate I have not noticed much difference because the speed limit is still low enough to prevent getting anywhere near what the motor will do and I really don't want to go that fast, not even on a track.
I believe you should spend more time going over your exact intentions and choose just what is necessary to achieve that. I have accomplished a spark blowout limited 305/322 lb/ft to the wheels dyno result so far at 13.5 psi but now the car runs as high as 18 psi with no blowout and before that I felt it was very fast. I can tell you now it is highly unlikely you will be able to push your motor to 600 hp on the street. There is not enough room among other things unspoken but understood. Build it for the way it will be driven 90% of the time despite your aspirations.
Alright I was just thinking 600, because I thought FieroX was making closer to 700 but only running 11's??? Plz. Correct if wrong. As for the stall, I'd be okay with it, it's only max stall. The car will still move at half that speed, but with the cam too. I want the 3250, hell intense recommends a 3750 for just the cam!! Guess your right about the 90%, I'm thinking 66mm then. Also my car does have the 2.6x gears I believe. So a smaller AR? Ever here about those hybrid turbos? Wouldn't just having a smaller turbine make it harder to spin the higher mass compressor wheel? Seems like lag would be more present right? Not saying I want a giant hot side like them holsets...
I thought fieroX ran a 10.08 ... I don't recall his numbers but from the grand prix forums I'm making an educated guess that he's got max 550-600 at the crank with his setup, more likely 450-500 considering how much lighter our cars are than gtp's.
Alright I was just thinking 600, because I thought FieroX was making closer to 700 but only running 11's??? Plz. Correct if wrong. As for the stall, I'd be okay with it, it's only max stall. The car will still move at half that speed, but with the cam too. I want the 3250, hell intense recommends a 3750 for just the cam!! Guess your right about the 90%, I'm thinking 66mm then. Also my car does have the 2.6x gears I believe. So a smaller AR? Ever here about those hybrid turbos? Wouldn't just having a smaller turbine make it harder to spin the higher mass compressor wheel? Seems like lag would be more present right? Not saying I want a giant hot side like them holsets...
High stall and numerically low gears, I'd think that would put a pretty good load on the tranny internals between the converter and the final drive. I would do lower stall and taller gears myself.
High stall and numerically low gears, I'd think that would put a pretty good load on the tranny internals between the converter and the final drive. I would do lower stall and taller gears myself.
I can understand where your coming from but for that extra couple hundred RPM of slip from the TC with the load of the high gear, It would be worth it to drive daily on the highway with the highway gears, not much city driving out here... plus if I need to I could launch that puppy hard, and cruise home on the highway turning at 2000 RPM, Just purely IMO. Now back to camshafts and turbo's... The cam I have is the ST3 I have 130# springs and a double roller too, Which would bring the redline up to 6500 right? I'm Also getting headers built... and lets just keep the 3250 stall for now. Since I have the higher stall I wouldn't need a super fast spooling turbo right? would something with a .70-.75 be better? Also I'm going intercooled but I think if I got a bigger wheel say 72mm-82mm I would only need about 8psi-12psi because of the extra CFM?? I'm new to the turbo game, I've read books about em am I close? Makes sense to me, big cam, high stall, light car, big turbo, but low boost... And highway gears to cruise.
PT6262 works very well for a 3800 street car. If you have the money for it I really want to see how a Pt6466 will do although it will make more power than you want. I wouldn't go over a 3000 stall. The 2750 on "formula's" car worked well, better than the 3500.
Definitely make sure you have good tranny cooler on it, the object of the high stall is to slip until you're at the stall point. With that said I'd expect it to slip some while you're cruising at 2000 rpm. It's been a while since I've looked into tranny work but I recall having a 2700 stall on my camaro years ago and not being very happy with it.
6262 turbo, 2500 - 2700 stall and St1 cam would be my recommendation.
Big cams make spooling the turbo worse. Big converters make top end slip bad, which leads to heat and converter failure. Bigger than a 6262 is not needed for 10s, I'm planning on 9s with mine.
A ST3 is a mid 9 second cam on heavy grand nationals.
My setup with a stock 2375 stall converter was able to make 18lbs on the foot-brake/2-step. Unfortunately when trying a 8 lb launch and 22psi run at the track, my input shaft decided to split in two. I am planning on a 2500 or so stall precision converter built to take the hp I'm trying to push through it, and finally make a full pass with my tune ironed out and hopefully a transmission that will hold. The 10.2 pass was a 4 pound launch, ramping to 18.5 in 2.2 seconds. Tune was not dialed in yet, and 1-2 shift was like a manual trans, due to programming issue. I now have a 8lb launch, 22psi in 0.5 seconds, good fuel/spark and trans shifting perfectly, but every time I go to track for the last two years, something in the trans breaks.
You don't need big parts to make 10 second power, over sizing stuff will actually slow you down.
Originally posted by LFiero67: My setup with a stock 2375 stall converter was able to make 18lbs on the foot-brake/2-step. Unfortunately when trying a 8 lb launch and 22psi run at the track, my input shaft decided to split in two. I am planning on a 2500 or so stall precision converter built to take the hp I'm trying to push through it, and finally make a full pass with my tune ironed out and hopefully a transmission that will hold. The 10.2 pass was a 4 pound launch, ramping to 18.5 in 2.2 seconds. Tune was not dialed in yet, and 1-2 shift was like a manual trans, due to programming issue. I now have a 8lb launch, 22psi in 0.5 seconds, good fuel/spark and trans shifting perfectly, but every time I go to track for the last two years, something in the trans breaks.
Not needed, I can make more boost than I can use on the foot brake. Trans break would be harder on cv shafts and transmission as well. When I did the test and made 18 lbs on the foot brake, the roads were a bit wet from rain, so I launched the car expecting it to blow the tires off. Instead, the drivers cv shaft sheared at the retaining ring groove. The car didn't move an inch, just broke the shaft clean. Had to push the car to the curb, go home, get a spare shaft and swap it out on the side of the road.
Wouldn't it be in lockup? Or do the aftermarket TC's not have a lockup clutch?
From what I recall lockup doesn't defeat stall which might explain my bad experience with it but I can not confirm that. It would however make sense considering you want the benefit of stall to be present at all times. It can go either way since converter lockup rpm is programmable stall is not but does vary with engine performance level. You may find yourself needing to apply additional throttle input to pull off moderately from a stop with the stall you have planned, but a good trans cooler is definitely in order for around town driving.
From what I recall lockup doesn't defeat stall which might explain my bad experience with it but I can not confirm that. It would however make sense considering you want the benefit of stall to be present at all times. It can go either way since converter lockup rpm is programmable stall is not but does vary with engine performance level. You may find yourself needing to apply additional throttle input to pull off moderately from a stop with the stall you have planned, but a good trans cooler is definitely in order for around town driving.
From what I've read based off aftermarket TC companies. Regardless of stall, most high performance TC's retain the mechanical lockup clutch. Which can be controlled by programming, or a manual switch. Otherwise I completely agree with you about the adjusted drivin style in the lower gears atleast. And yes Trans cooler is on the list. I should retract my previous question about bigger turbos and less boost. That was wrong cfm is cfm. Just it would be easier on the turbo if it was bigger. I agree the p6262 looks like what I'd want. Just the boost adviser freaked me out by recommending 76mm+ turbos you know?
Also a question for you guys, what's the average spool rpm for the p6262? If I'm cruising down the highway 2500-3000 I wouldn't want it to be boosting for mpg sake, with having a large cam, a bigger stall, and it being my daily driver. I'd be fine with a turbo that doesn't hit peak boost until around 4k rpm. Of course I have no experience with turbo cars. But for a dedicated street car does that sounds right? Street racing is 99% roll racing so I'd be fine with lag there. I'd only track it a couple times a year.
You won't have any boost without load. just cruising at any RPM you'll still be in vacuum in most instances. unless you are going up a steep incline.
I know that now, weird concept. Just like even if you have the RPM you still need flow through the throttle to boost ie. Not sustaining speed but increasing load as you said. If anyone is interested my project has slowed down as I kept piling on upgrades/work. But scored a Precision P7667 for my 3800. 67mm with a .68 AR.
