3sgte exhaust manifold questions

[headshotnz]

Whats the difference between a gen 3/4 manifold compared to a gen 2.

Looking on DPR and pondering the idea of a t3 manifold, but i want one with an external wastegate port.

They only seem to have a manifold with no wastegate port for a gen 2.



Im also new with turbos, do most aftermarket t3 type turbos (that can be found on the likes of trademe) come with internal wastegates, if so, what is needed to bypass the internal wastegate.

also assuming a aftermarket intercooler would be a must for a sw20 if i was going bigger turbo?

Any body have any experience with the DPR intercooler for sw20?

Reasons for uprading turbo is because i dont know how long my ct26 will last (done 220ks)(and have no service history) and good luck trying to find a ct20b with a pricetag that i dont need to sell a limb for...

Thanks in advance

[Al]

http://www.full-race.com/store/turbo-ma ... ifold.html

[headshotnz]

Holy jesus. Yeah when lotto rolls around.

DPR manifolds are a quarter of the price.

[loudstealthGT-Four]

The difference between Gen 2 and Gen 3/4 is the exhaust ports, you can not fit a Gen 2 manifold on Gen 3/4 head and vice versa

If you don't want to use an internal wastegate port then just remove the wastegate actuator and weld up the wastegate flap.

Holy jesus. Yeah when lotto rolls around.

DPR manifolds are a quarter of the price.

and theres a reason for that, quality costs $$$

[samlloyd]

Whats wrong with using a standard internal wastegate for your motor?

[headshotnz]

Whats wrong with using a standard internal wastegate for your motor?

Nothing at all except loud noises

[solitaire]

Whats wrong with using a standard internal wastegate for your motor?

Nothing at all except loud noises

I never understood that, wouldn't it be the same level of noise? an external wastegate still goes through the same exhaust system....

[sergei]

Whats wrong with using a standard internal wastegate for your motor?

If he will be using CT20b, the factory waste gate is not up to the task with free flow system, which results in freeboosting.
Otherwise there should be no need.

[iOnic]

Whats wrong with using a standard internal wastegate for your motor?

Nothing at all except loud noises

I never understood that, wouldn't it be the same level of noise? an external wastegate still goes through the same exhaust system....

But is often a much bigger port than the stock wastegate port so slightly louder. Unless your flat cap is designed not to fit when in the straight ahead position in which case a 20" dia pipe coming off the wastegate and venting flames into your engine bay sounds like a perfectly good idea.

[Al]

Whats wrong with using a standard internal wastegate for your motor?

If he will be using CT20b, the factory waste gate is not up to the task with free flow system, which results in freeboosting.
Otherwise there should be no need.

Only if you use a shitty downpipe.

I have ct20b. Berk 3" downpipe and a 3" mandrel bent bit of pipe about as long as my arm with no mufflers. Zero boost creep. Holds 0.6 bar to redline with boost controller off. Holds 1.1 bar to redline on low boost. Holds 1.35 bar to redline on high boost.

[Dell'Orto]

Old MR2 never overboosted (once we plumbed in the screamer)

[diss7]

My old st205 overboosted when I had a custom DP made. It turned out that the pipe leading from the internal wastegate was too small, and wastegate couldn't fully open. Once this was fixed, it could hold boost.

[sergei]

As I said many times, I had factory waste gate flaps removed on the stock CT20b, the ports machined to bigger diameter and downpipe was separate for turbo. With no waste gate (basically venting to atmosphere straight from the wastegate ports) I would still get 1 bar boost at 5000rpm.

I don't know why I had this problem and others don't.
Initial setup was stock CT20b turbo/wastegate with XS Power downpipe and 3" no restriction exhaust, at 5000rpm I hit ~2 bars easily.
Here what I went through to get it sorted:

Grind and hammer XS Power down pipe to make sure the waste gate flap is not catching, operate the wastegate flap to make sure it can fully open (it did).
Try the flap completely forced open - still made boost.

Ditch XS Power down pipe, in favour of separate 35mm wastegate feeding off the enlarged factory waste gate ports (while the turbo had dedicated pipe). Result was negative, as a test I completely removed 35mm wastegate, effectively venting the factory (now enlarged ports) to atmosphere - 1bar at 5000rpm was produced with this setup.

The turbo was brand new (Warwick deal) CT20b steel. The engine is gen1 3SGTE with gen2 manifold to accommodate CT20b/twin entry.

To fix issue I redesigned the thing drastically - now between the turbo and manifold there is a sandwich plate, maintaining twin entry path and bleeding into two separate 35mm external wastegates.

As I said I don't know why I would get this overboost problem, while others don't but I am not making this up - Evil_Si is who did all the welding and fabrication work can confirm this.

[diss7]

Its not a question of whether you're making it up or not. I think the whole point of these forums is for members to discuss their experiences.

Regarding the original post, you seem to be going down the T3 path because a ct20b is too expensive? But you're spending money on manifolds and other jazz. How fast do you want to go? A ct20B will give you boost early, so great streetability, and as lone as you're a better driver than Akane, you will run 12's with one, which is quicker than most cars you will come across.

And if you want to get more power than a ct20b will push, you are talking big money, as alot OEM gear gets unreliable at this point.

If you're pushing a ct20b hard though, you can still go faster. Clutch, flywheel, tyres, weight. That's what I'd do anyway.

[Akane]

lulz still class C4 winner of the day, fastest CT26 with I/H/E full trim MR2 as well.

[sergei]

CT20b is good up to 200kW at 4wheels (whatever that works out to be in 2WD). If you want anything more than that you will need a different turbo.

CT20b is suited really well for 3SGTE - it gives you a solid boost right through rev range, and is a lot more efficient than CT26. Plus it is a bolt on for Gen2 engines.

[Anth_555]

ct20b is by far cheaper. if your keeping everything stock on the moter your never going to max out a ct20b. even with a computer a ct20b is going to push the limits on a gen2 fuel system if not max it. your going to spend more on a turbo alone then what a ct20b cost and then have to set it up. changing a turbo is not as esay as people think.

[gt4dude]

i had overboost with a ct26 alltech jobbie, factory downpipe, factory 2.25" over front subframe, 3" aftermarket from there

just went thru 1.2bar and cut

[kim0663]

Just get the t3 style turbo you're looking at, and a manifold to suit and keep the internal wastegate. Going external makes things much more expensive.

If you want the cheapest alternative that gets you what you want ? = ct20b + wastegate noise

make up a downpipe with a ct26/20b internal wastegate venting to atmosphere.

Personally, ct20b is a decent and easy to fit but wouldn't say it is something fast... afr start leaning out (obviously 100% duty) on ct20b + gen2 at 1.2bar if all the fuel system is well. At 1.3bar, my 3s was around 12:1, maybe a tad below

1.3 bar is nearly 19 psi, I don't think I'd want to push a ct20b much further than that.

[headshotnz]

Thanks every one for the very usefull information!

Sorry i didnt reply very quickly, i had to sum it all up and do my research too know whats going on.

Iv been looking at the idea of a devorced/seperate downpipe on my ct26 for now.

Who would make such a thing, the only manufacture i can find is EMS

http://www.emspowered.com/storefront/in ... cts_id=484

Ideally i would want 250-300kw at the wheels. but that is a wee while away for now.