Hey guys,

I have a question in regards to upgrading wastegate size from 38mm to 44mm on my ramhorn manifold. I recently brought my car in for a dyno tune and the it's putting down good numbers as expected but I'm outgrowing the 38mm wastegrate above 7800-8000rpm. Boost holds solid 18psi until that RPM and then creeps. Tuner did some test and the 38mm gate is just too small for my 6466 turbo.

I took a look at the inlet/ outlet sizes on the 38mm gate and the inlet is 1-3/4" or (44.45mm) and outlet is 1 1/2" (38.1mm). Seems like the feed pipe should be large enough for a 44mm gate and I would just need to cut the Vband off my manifold and weld on a 44mm vband.

Would this work fine? Seems like the outlet is going to be the limiting factor here not the inlet size.

Or would it be best to add another 38mm gate if I have the room?

Best Regards,

 

Most of the times is more about wastegte gases separation angle on the manifold, than a wastegate issue, especialy on that boost pressure.
In that case bigger wastegate is a band aid. In that 66mm turbine wheel MAYBE the manifold is ok and you really need a bigger wg but i give it 3/10 chance
Give us a picture of the manifold/wg.

 

Thanks for the response! I should have post a picture from the start. Sorry for little information on the manifold. It's a BWR ram horn manifold. Turbo is a 6466 T3 .82 housing. I have a 1.5" dump pipe that runs to the bumper right in front of the wheel. about 2.5' long with no sharp bends.

I just notice that the outlets are a smaller dia. than the inlets of the WG's. Now I'm seeing that Precision and Turbo Smart offer upgrades to 40mm to a Tial 38mm that bolts right on. How well would that work given the feed pipe is the same size? I'm under the impression that the best route is to cut off my current feed pipe and weld on a larger pipe for the 44mm WG. It's confusing.

I also understand about the wastegate placement could be adding to this problem but it seems to do it's job until it's really moving some air only at 7800-8000RPM does it start to creep. Is 18psi still considered on the low side of low boost when talking 30-35psi? Doing research and reading through information on Tials website, they specifically say that large turbo and low boost needs a larger gate. So, I'm wonder if maybe the 38mm is just to small and it's backing up into the stream moving to the turbine and raising boost.

Simply being able to bolt on a larger wastegate would be a very easy solution but sounds too good to be true. Seems like just upgrading wastegate size with the same feed wouldn't do what I need. Unless the feed pipe I.D. is sufficient enough to feed a 40mm WG and use it to it's full potential. I'm not even sure if 40mm would make a large enough difference b/c it's creeping at 7800 and I'm going to 9500RPM.

 

This could go either way. Although I agree in some aspect that the use of 44 mm gate is a bit of a Band-Aid, depending upon the wastgate spring that you use, (and the amount of retarded timing that the tuner has on the car with such low boost pressure for such a large turbocharger,) you may actually need a second 38mm wastegate, versus a single 44mm.

keeping a turbocharger at that size and running lower boost pressures like 18 PSI and below, with such a large diameter equal length manifold, it really makes it rather difficult for a single 44mm to perform it's duties properly. That's not to say that it could work, it's just that we don't really know the true purpose of your car, considering the size of the turbocharger that you're using, and the range of boost pressures that you're running with your tuner's methodology.

All that said, I think it would be best to first change the flange to a 44 mm gate, and use it, then if the problem still continues, even after some boost control adjustments, a second wastegate is in order. Also, make sure that the tuner is not retarding timing so much in order to be conservative or "safe".

 

Thank you for some insight as I hold your input with high value. When I get the car tomorrow I will download the map and look at the ignition timing. I'm not one to tell the tuner how to do his job even though I have a decent understanding of tuning. I'm not entirely sure that the map is at it's final state. We were going for 700hp on E70 at the moment and 800 on E98. At this point we were just getting to make full passes and taming the PSI with an 18PSI spring. Got it to stay stable until it hit 7800 then it spiked to 23psi. The intention of this car is low boost 18psi on the street and high boost +30psi at the track. 1/4 mile racing.

When you say "first change the flange", do you mean to cut the entire feed pipe from the manifold and weld a new larger feed pipe in from the manifold to WG or to just cut the 38mm flange off and weld on a 44mm to add the WG. The diameter of the pipes are very similar. You thinkin taking some side wall out of the ID of the feed would make up for a larger pipe? They seem so close in size.

I also did consider just plumbing in another 38mm since the price is cheaper than a 44 and would have to plumb in a new pipe anyway. Plus a 38mm will leave me more room in the engine bay. Or like you said maybe add the 44 and then add another if I need it. Just trying to get this done one time b/c I have to tow the car over an hour to get to the dyno. So towing it in and then having to tow it back to tear it down and reweld would be a bummer.

Thanks for the help so far. I appreaciate it.

 

I'm sure you can't (nor shouldn't) Tell the tuner "what to do". I'm not one to look at a lot of fuel / ignition timing maps, so don't worry about sending it. I just didn't know if the tuner tended to ever divulge to you whether or not he kept things "conservative" or not for the tuning. I'd honestly would concentrate on the power output of the car for "street duty" rather than boost pressure. But I will say that as long as you're trying to control boost to a low level, regardless of the boost controller, you need a larger gate, for something that big. Don't worry about 18psi so much. But it is spiking to 23psi either because of A) solenoid isn't / can't working hard enough to control the excess pressure due to the turbine wheel efficiency (I'm waiting for AZ_CIVIC to gloat here. ) B) you're using too light of a spring, and need to go heavier (as your turbine wheel is just really efficient, and too much for your spring to handle in the upper rpm band.. This is especially true with the type of manifold you have and the CFM flow rate of your cylinder head).

If you want to do this only once, and use such a large turbo for both "street" and drag duty, really just add another 38mm wastegate and reconfigure the manifold. 1.75" runners + Big turbo + Lower boost pressure + High knock resistant fuel = too much exigent exhaust gas to control boost. Going 44mm is really not going to solve the issue for this purpose.

 

Hmm interesting. So would it be wise to swap my 3 port MAC solenoid out for a 4 port while plumbing in another 38mm wastegate? Thanks for your explanation.

 

I was wrong probably, the manifold wastegate routing looks good.
Shodan is trying to say that since the turbine wheel is so free float its easier for the exhaust gases to go the turbine wheel than the WG path.
Do not underestimate every mm on circular area. Its π x R^2. Every mm increases a LOT the area and cfm.
38mm has area of 1134
44mm has area of 1520 thats 35% increase in area and cfm with only 17% increase in diameter.
Rpm 7800 to 9500 is 22% more exhaust gas flow in theory so youll be ok with a 44mm wastegate again in theory.
I really like the 50mm turbosmart progate. 50mm has area of ~2000 and its not super huge like the very big 60mm gates

Also is that gen2 precision or gen1 ? give us some feedback on engine size cams and when it starts/full boosts at rpm.

 

Bolar,

Thank you for breaking it down in math for me. That is really the information I wanted to know. What the actual difference was between the two area and CFM wise. I figured even though it's a marginal difference relative to me, relative to CFM it probably makes a large difference to warrant a new WG size ya know. I was just really confused by the adaptor flanges available. Thanks you for clearing that information up for me!!!!

The turbo is a Precision Gen 2 unit T3 .82 housing

Engine
2.0 B series block Benson sleeved
10.5: 1 compression Forged JE pistons upgraded wrist pins
Manley turbo tuff rods
LS crank balanced to 10k RPM
ARP hardware
ARP mains line bored to spec
GSR head with mild port work
unmodified Skunk 2 Ultra manifold with 2,2 spacer
74mm Throttle body with 90 - 74 adaptor plate
OEM ITR cams
Ferrea 6000 series valves and springs
3" exhaust to bumper exit
1 3/4" dump pipe that follows bumper exit exhaust
ATI race damper
38mm Tial WG
Greddy Type S BOV

The setup is making 500whp right now at 7800 rpm and boost creeps up so we stopped until we can control the creep.

 

Here are some pictures of everything installed and routed.

 

You use turbo tuff with the arp2000 bolt right?
Id like to see boost charts on this turbo. Maybe later if ever
Ill be running an 84MM ls crank turbo setup soon too.

 

Yes it's got upgraded ARP rod bolts.

I'll get with the tuner when I bring it back for the big power pulls. Will be switching to E98 for the 800hp pulls. Just let me know what information you want to see and I'll see what I can get for you. I couldn't find too much information about this turbo on a Honda engine.

 

You don't have to. Not necessary.

And co-sign on the Progate 50mm over adding a second 38mm. I admit, most people using such a large turbo would have a divided housing

 

Shodan even on a T3 housing? I would have done that if I went T4 housing but didn't think it was needed on a T3. Thank you for all the suggestions. I'm going to get the car back tomorrow and I will get some more information when I do and make some decisions. I'll update this thread when I have more information to share. Thanks guys!

Ryan

 

The volute size is what matters, Not The flange configuration.

 

Does precision has real divided housings or the meh half divided ones?

 

Precision only uses the divided housings, and not true twin scroll housings. The effects of twin scroll, in actuality,only work with smaller turbocharger applications, not with something this large. Even the EFR boys that designed their admit to that with their larger applications.

As long as Precision knows that people on the interweb will continue to drink the kool-aid of false twin-scroll nomenclature, they won't change a thing... and won't need to. Because the internet knows all.

 

After talking to my tuner extensively about the wastegate he said to just upgrade to the 46mm Precision WG. At this point I'm not paying for any more tuning so I figured why not. Only going to cost me time and a little money for materials to weld. With that said, I bought the new wastegate and also bought 1.75" SS pipe for the inlet to the WG and bought 1.75 to 2" out to the bumper for the outlet side. Going to angle the feed pipe at a nice angle to help the air move into the wastegate. I'll update the thread when I'm done. I still haven't pulled the tune from the ECU yet.

 

 

That is excellent to hear man. I'm thinking about lowering the spring a little to 15psi so I can control more boost with BBG. 500hp on the gate is kind of high for low boost.

Thanks for responding with some experience to my situation.

 

 

Thanks man. Yeah this really is a track car BUT being in New Orleans, "Da Pad" is the closest we have to the track without towing an hour. One can say that "Da Pad" is almost as good as the track for 60' but gets sketchy up top with high hp and spinning. So that would be the "street" I'd want to run on. Otherwise I'd probably cruise it to a meet or two on a nice day.

The exterior is wrapping up. I got my Push Performance front end not long ago and just plan on wrapping it with carbon fiber 7D vinyl that I already purchased. Thank you for the compliment with my build. I built the car myself.

 

The car is beautifull.
Imo precision wastegates are too iffy. Reliability wise.

 

If it has a problem I can revert back to Tial 44 as they use the same flange. We shall see how it goes. Hopefully no problems with the Precision WG. I have read the same thing but a lot have found success. At least if I need to change it, it's a matter of ordering a part and swapping and not taking the car back home and having to reweld again. Fingers crossed man and thanks for the kind words. I will post the results after I get it all on and on the rollers.

 

Precision gates = creep city with frozen valves.

Going back to the 44mm valve solves nothing. Get a real valve and solve this **** already. Quit wasting your own time.