Single turbo and wastegate recommendation needed
 

Hello guys, I need some advice on building a street friendly single turbo 400. My goals are 600-650 hp with a single turbo no intercooler with log manifolds.
So far I have a low compression 400 with ported 6x4 heads,2801 cam, adjustable valve train, flat top pistons. The car is about 3800lbs with a built th350 trans, 2500 converter. Highway gear that I like since I plan on going to meets with the car and drive it as much as possible.
My question is what size turbo will spool up soon and work in my rpm range of 2500 to 5200 rpm. I see a lot of s475 reconditions but I think it might be too big. I also prefer a non v band cold side outlet turbo. Also this is a low budget deal so I been looking at eBay turbos. Also what size wastegate.
I’m tempted to run a turbo with an internal gate. We run them on grand nationals with pretty good control. Any thoughts are appreciated, thanks Henri…

A single s475 is not a big turbo for a 400 cid engine.

Tom V.

something like this with 2 44mm gates would do the job IMO .. this would be as cheap as it comes... haha

https://www.ebay.com/itm/36311517088...Bk9SR-im3rq-Yg


https://www.ebay.com/itm/20433112367...3ABFBMtMGYu75i

You can go with a much more efficient turbo than a BW.

I put a VS Racing 7875 Gen3 with a 1.25AR on my LS3 (376 c/i) with a single 50mm wastegate on the passenger side of the exhaust crossover (priority charge exit) and made 635rwhp (around 830hp flywheel) and the turbo nosed over at 6700rpm through a 6L80e automatic. IMO this turbo would be a fantastic size for a 400" Pontiac.

The above statement says you are a buyer vs an EXPERIENCED Turbo Engineer with your BW statement about Turbo Efficiency.

Tom V.

Tom critiques turbo. Doesn't recommend one
Krisr recommends one he personally used
YoU'rE nOt eVeN aN EnGiNeeR!!! :rant:



Henri: have you looked up Firechicken's older posts? Twin turbo'd second gen bird, using the "junk" 301T stuff.

Ha, ok.

Yeah, PY... the Twitter of the Pontiac world.

The BW475 is a very good turbo, very spicy in the top end and also very heavy on the corner it's mounted. But, you know, it's much easier to just buy your turbo because it's the first one that pops up on Google Ads. No need to crawl through the maps of many turbos, factoring in converter, gears, tire/wheel sizes, car weight, fuel quality, target boost pressure, piston ring gap and engine management but most importantly, one should never comment on the PY boost section in fear of upsetting the retired boost engineer. But when the advertisement said I would make 635whp at 10psi on the hub dyno with me tuning it in a car designed purely for the street that also just finished a 600 non-eventful-and-reliable mile trip because the wifes Subaru has head gasket issues, god dammit, I just had to have it.

Have fun guys! I'm out. :rain:

Kris if you want to be taken seriously you probably need to quote yourself in your sig, mate. And not bother with any of this personal experience nonsense.

I have not seen any Engines mounted on hub dynos going down the actual race track. Hub dynos do not include AERO or tire losses.

Facts vs partial knowledge of actual racing influences. Bragging, nothing more.

Tom V.

Same BS happened with Carb Flow Advertising. Instead to using a standard 20.4" H2O test flow point, you go to 28" of test pressure as it reports a bigger carb flow number. ADVERTISING.

Tom, just be quiet mate. You're making yourself look like an old fool now.

Cheers!

The combo Charlie66 posted looks pretty good. Personally I'd stay away from the super-cheap eBay or Holset turbos. A BW will work, but there are (in my non-engineer-opinion) better options out there today from places like Pulsar and VS Racing, as KrisR said.

You haven't mentioned what your compression ratio is, if you're going carburetor or EFI (and what management), or if the bottom-end is forged, or if you've upgraded the oil pan/oil system at all. All of this stuff would affect what exact turbo I'd suggest because it will change how closely you have to manage your boost/cylinder pressures.

Personally, I'd do as Charlie66 suggests and go for x2 44mm gates for better control compared to operating one 60mm+ sized wastegate. An internally-gated turbo will also be nice and responsive, though I don't know of many in the size of frame you'll be after to suit a 400ci engine.

So what's your recommendation for the guy who started the thread? So far you've offered nothing pertinent to his question.

Look up the Dec. 2009 CarCraft article "ludicrous pontiac power". The engine featured is very similar to the engine you describe.

Thanks Ken C.

Tom V.

As far as the comment from the guy from Sidney.
Some have OPINIONS and others have years of actual experience doing the job for big money.

TV

What? I'm pretty sure Ken's well-intentioned
advice was actually intended for the OP.

https://media.tenor.com/R-RjmM1aii8A...dy-crushed.gif

Tom your arms must get tired from patting yourself on the back all day long.

Going with T4
 

Thanks for all the replies, I’m going to go with a 7875 T4. Main reason is that the borg is seriously heavy, I’m going to mount in close to the firewall on the right side. The car is a 62 Catalina and I’m going to run aftermarket AC as well.
Contemplating an e85 carb instead of fuel injection.
I have a long block mocked up in the car and going to do stock manifolds with a crossover underneath like a Buick GN. Trying to keep the hot side piping underneath. Will post up some pictures of progress.

Funny thing is I did the JOB for a BIG 3 OEM for 40 years.
2016 Ford won Le Mans with my stuff.

Those are FACTS not opinions like your post Bill Bowman.
Plus some Pe*is envy on your posts obviously.

The facts are out there no matter how much you think you can down play
them.

Tom V

You'll love it mate. One thing I would caution you with though is the engine management side of things. E85 carbs are great if you're going to run just E85 and a timing curve dedicated for that fuel where if you're running a good electronic engine management with a flex fuel sensor you can reap the benefits of using any type of fuel available to you and have your engine management adjust on the fly your fuel stoich set point and your spark tables. I run flex pretty much on any car because here in Australia we have 98RON and E10 (94RON) fuels in abundance. E85 is rare. So most cars I tune i'll setup for 0% ethanol, 10% ethanol, 50% ethanol blend and 70+% ethanol. Our E10 fuel will need timing pulled away in the mid range and at peak torque compared to 98RON and E85 but E10 is roughly 30c/litre cheaper here so just for normal street driving it helps the hip pocket somewhat. Plus you can also throw in flex boost control so when you do throw in the party corn sauce, it will party a bit harder where as if you're going to run a lower octane fuel or less ethanol you can run less boost. Something to think about....