Hoping that someone with some experience could help me make an informed decision. I'm putting together a mild 6.2 with a single 72/75 .96AR with a 212/218 cam, limited to 5500rpm. It's my first turbo build and I want to start out with 3lbs of boost. My question is would I be able to control the boost to this low level using two well placed 38mm wastegates or would I need to go up to 45mm wastegates? Thanks for any help.
Mike Maner
I think you'd be good with those. I went with two 46mm WGs but I'm ultimately planning to run about 28 psi.
There is no reason to limit RPM.... just keep it under 6500-7000rpm and it will live a long and happy life with dual valve springs.
BTR STAGE 1 TURBO CAMSHAFT V2
217/22X .616"/.616" 113 LSA
This cam would drive like a kitten.... that turbo you are choosing is also going to bottleneck quickly on a 6.2 liter. Let the turbo do the work and if you need more power.... simply turn it up when you are ready. Twin 38mm gates is what I have on my setup below.
I had a tiny cam in a 6.2 and it made 1200rwhp+ shifting at 7500rpm+ with stock LS3 intake and ID1700 injectors (T56 Magnum/8.8" 3.31 gears) on e85. You could turn the boost down and drive the car anywhere. 14psi made 1060rwhp (MAST LS3 heads on it)... without using boost by gear/time (ramping it in) you couldn't really pour in any real power (1000rwhp) until about 3rd gear on drag radials.
What car is this going in? What do you want to use it for mainly?
BTR STAGE 1 TURBO CAMSHAFT V2
217/22X .616"/.616" 113 LSA
This cam would drive like a kitten.... that turbo you are choosing is also going to bottleneck quickly on a 6.2 liter. Let the turbo do the work and if you need more power.... simply turn it up when you are ready. Twin 38mm gates is what I have on my setup below.
I had a tiny cam in a 6.2 and it made 1200rwhp+ shifting at 7500rpm+ with stock LS3 intake and ID1700 injectors (T56 Magnum/8.8" 3.31 gears) on e85. You could turn the boost down and drive the car anywhere. 14psi made 1060rwhp (MAST LS3 heads on it)... without using boost by gear/time (ramping it in) you couldn't really pour in any real power (1000rwhp) until about 3rd gear on drag radials.
What car is this going in? What do you want to use it for mainly?
i agree a s400 chassis is what id use with a 6.2 for sure..that cam should go 6400 also id guess. , as for gates that should be fine..3lbs aint shit
Guys, I really appreciate all of your help. I put the rpm limit in place because of the displacement and the size of the turbo along with the .96AR. I may be being to conservative on the rpm as I don't have any experience with turbo motors. The goal is to build as much low and midrange torque as I can. It's a street only car. What I enjoy most is feeling the car pull hard thru the gears during normal/spirited driving. Thanks again for all of your information.
I should have added that my biggest concern with the wastegate sizing is that I be able to control the boost to the low levels that I want to run without spending more for them than need be. I want to start at 3lbs and as I learn more I'll move up, but I'll probably never move past 7lbs. Thanks again for your thoughts.
Mike
Mike
When you get the want for more HP, s480 with 87mm turbine wheel 1.10 ar housing would be obnoxious on a 6.2. I do not think you'd notice a difference in spool being 376 cubes on ethanol.
You'll get bored with 7 psi pretty quick.
With my car it was a little much at 15 psi on the street.
Keep some room for more turbo.
With my car it was a little much at 15 psi on the street.
Keep some room for more turbo.
Didn’t see mentioned that gate size isn’t near as critical as gate placement. Placement is more important IMO. People with poor placement are usually the ones thinking they need 66mm wastegates. I’ve never run more than 38mm. Though I don’t run 3psi either.
I’d think a healthy LS3 would provide all the down low TQ most street cars need? Esp. if you aren’t on a drag radials?
The last thing you should worry about it not having enough power down low with an LS3 on the street. I’ve built a ton of smallbore engine LS setups and response and power down low was never an issue. Even with relatively “large” turbos.
I get not wanting to build a race car. But have you plotted that turbo out on a compressor map to your basic setup and RPM range?
BorgWarner MatchBot
I’d think a healthy LS3 would provide all the down low TQ most street cars need? Esp. if you aren’t on a drag radials?
The last thing you should worry about it not having enough power down low with an LS3 on the street. I’ve built a ton of smallbore engine LS setups and response and power down low was never an issue. Even with relatively “large” turbos.
I get not wanting to build a race car. But have you plotted that turbo out on a compressor map to your basic setup and RPM range?
BorgWarner MatchBot
ForceFed86, my concern about the low end power comes from my experience with my earlier cars. They were either 454 or Olds 455 powered and they were built with low and midrange power in mind, and they were a blast to drive. The turbo is from Forced Performance, and as far as I know no compressor map is available. I think I'll be okay with the size of the turbo for what I want, they do offer a 1.25 AR turbine housing that I would be willing to try if the .96 proves to be to restrictive. Thanks for your input.
I hear ya… Unless heavily modified though, a healthy LS3 would run circles around those motors.
at 72/75 is pretty similar to the small T4 S400sx3 line. You can use the S471 map to get an idea. PN 177248. The map below says its for this PN. If that's true you can see its a poor match.
The issue is with such low desired boost you may not even make it on the map and can be on the surge line.
For example with the S471 which is a 71/75 T4. This is what I see with a 6.2 @ 3psi. For example with the S471 which is a 71/75 T4. This is what I see with a 6.2 @ 3psi. Even 7psi isn’t on the map. The first dot is 2000rpm, last dot is 5500rpm
![Image]()
at 72/75 is pretty similar to the small T4 S400sx3 line. You can use the S471 map to get an idea. PN 177248. The map below says its for this PN. If that's true you can see its a poor match.
The issue is with such low desired boost you may not even make it on the map and can be on the surge line.
For example with the S471 which is a 71/75 T4. This is what I see with a 6.2 @ 3psi. For example with the S471 which is a 71/75 T4. This is what I see with a 6.2 @ 3psi. Even 7psi isn’t on the map. The first dot is 2000rpm, last dot is 5500rpm
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