34mm Restrictor Solutions?

Now I have my GT2871R - which means I also need a restrictor.

I'd like to keep it removable so I can runt 2 maps (one for track/hill climb, one for rally w/restrictor).

I'd like to make sure the restrictor also does not create strange turbulence as air approaches the impeller.

My thinking is that the GT2871R is popular enough that this has been done by lots of folks?

Thanks,

Vittorio -

Popular enough?

Uhh, sure, why not, I'm not prejudiced. Some of my friends are GT2871Rs...

What's the real question? HmmmmmmMMMM?

You're going to find somebody to carve up a new restrictor and match the transition so its nice, and removable. That means somebody needs the compressor housing and TIME since that's a onesey and every place I know hates oneseys. They want runs og 50-75.. 400 ain't bad. I ran 400-450 coffee tamper things in stainless and various colors nylon while Bob was setting up the machines to run my tubes.

Show us a photo.....

Tell us what hoses, what current rules---how many to make? etc

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

If you have someone that can make it, i might be able to get you a drawing.

I have had a couple made for GT28RS, and most should be the same besides a couple of dimensions.

Interesting tho that you went with the 2871. The 28RS doesn't really like the restrictor, and the 71 would be a little worse probably. Make a nice unrestricted turbo tho.

I'll get some pics and dimensions up this eve JVL.

As for rules - seems pretty uniform across sanctioning bodies in US:
-- Max 50mm from impeller wheel
-- Min 3mm worth of restriction
-- 34mm min in any temp range

Chris - which turbo does like the restrictor? I've read a bunch on the inter-web, seems like there's at least a few folks that have run this turbo w/restrictor.

Not knowing very much about fluid dynamics, turbo's and what not - what are the current opinions? (I have a fairly low ratio tranny from the '84 4k, so spools in the 2500-3000 rpm range should be fine. My target is 300whp.)

Quote
vbares
Chris - which turbo does like the restrictor? I've read a bunch on the inter-web, seems like there's at least a few folks that have run this turbo w/restrictor.

Not knowing very much about fluid dynamics, turbo's and what not - what are the current opinions? (I have a fairly low ratio tranny from the '84 4k, so spools in the 2500-3000 rpm range should be fine. My target is 300whp.)

On the restrictor you will not make more than ~315whp and I suspect you'll fall well short of that goal without lots and lots of work to optimize things. The problem with having a turbo for both is a turbo for a restrictor is fine running out of breath on your car at 5500rpm, and that same turbo off the restrictor will feel lame up top. I went to a V-band setup on my Evo so I could swap turbos quickly depending on what kind of racing I'm headed out to do. Added bonus of V-bands are no gaskets to blow out.

For a restrictor, you want spool very early (think turbo diesel type power delivery), so a turbo like the 2560 is likely a better choice. If you have unlimited sums of $ to throw at the problem a Garrett TR30R makes a great solution for on the restrictor, but off the restrictor its a weird powerband. From what I've heard off the shelf Garrett BB turbos don't like antilag.

I've heard that the OEM Mitsu turbos respond much better to antilag.

Dave

I've been reading a bit about the restrictor really limiting HP at the top end - and your comments of 5500 RPM is consistent with that...

So, perhaps I'm chasing the wrong tail - I mean, what the hell does 300 whp really mean anyway? It would seem to me that having torque is a pretty cool thing for tighter twistier stages - of course HP is good too for the fast flowing stages - so its all trade-offs.

No I don't have a big budget - in fact this decision to go to a 'proper' turbo - meant that at least one or two rally's won't be run

From my readings the GT28RS is a slower spooling turbo compared to the 2871r - so I thought that was going in the right direction. My ECU does have anti-lag capabilities - but my wallet is telling me that would be a bad idea - so lets leave that out of the equation.

What else makes a turbo better tuned to a restrictor ?

You might talk to Mark Malsom about restrictor design. He did a big research project on the flow for varying designs once. He's not yet made enough friends with machines to be able to make anything yet though.

This thread is relevant to my interests. I have a 2871 and am needing a new restrictor....

Tonight I cleaned the pistons and rings, just to make sure there was not debris in there. New rod bolts and nuts. Torqued and done. A bit scary as that is the first time for me - and I now have extreme metal breakage = $$ traumatic syndrome

ok - here are some pics of the Turbina -

The impeller to top of intake measurement is accurate - as I measured w/a straight edge...

The ID of the intake is 71mm (is this a coincidence that its the same as the inducer size?)

A/R is 0.60 (cold side)

I've seen several examples of restrictors today - I think a big lump of Aluminum and a few hours of a machinists time might get me there ?

Quote
vbares
The impeller to top of intake measurement is accurate - as I measured w/a straight edge...

The ID of the intake is 71mm (is this a coincidence that its the same as the inducer size?)

A/R is 0.60 (cold side)

I've seen several examples of restrictors today - I think a big lump of Aluminum and a few hours of a machinists time might get me there ?

Vittorio, I'm sure there are a bunch of experts who would agree and the only reason they haven't made their own is because they were busy---not the fact they can't run a lathe and have never made a restrictor, but the few that I have had anything to do with we needed to mod the compressor housing so the transition from restrictor to compressor housing was uninterrupted... So a chuck of alloy, some lathe and some mill time to bore the housing out, then some drill and tap time.
Here's some that I know:


Or:




Seems the poms want a fair bit:
http://www.owendevelopments.co.uk/products/product-detail.asp?prodId=51&catId=7&subId=-1&imgId=b

Like GBP185.

Seems we're back to that one set up and do as many housings as possible in one run.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Thanks John.

Yes - those are the basic designs I've seen. So the question is - how transparent does the transition need to be? I had also thought of lopping off the intake and making a flat area where a restrictor could be bolted in...then a non-restrictor venturi could also be made - (should have just put a damn V8 in the car )

Perhaps DaveK is correct in that two cold sides are needed - one w/restrictor one without.

To get to the 50mm mark - I'd have to take at least 5mm off the intake anyway (if I were to weld the restrictor on).

I could see an insert working that tapered out to the edge of the existing taper...I've got a really good machinist in the neighborhood - may just bring it to him to see what he thinks. It really depends on how good that transition needs to be...

On another note - DaveK - you're probably right - 2560R, may have been a better bet w/the restrictor (smaller turbine, faster spool), but i think I would have liked a 2571r now that I understand the numbers better

http://www.turbobygarrett.com/turbobygarrett/tech_center/gt_basics.html

The WRC turbos have a very small turbine, and a fairly large compressor snail...and of course a very large budget.

I have a 2871R but I forget what compressor and A/R housing it has. I spoke with Garret about the usage and sizing and they recommended the one that I have. Supposedly, Buffum ran it in his cars at the time so I figured it was good enough for me.

I'll try to dig up a picture of my restrictor, it was made by a guy in Arizona I think. It has a much longer lead in than most of the ones that I've seen.

However, I haven't been able to make more the 15lbs of boost and never figured out what the problem was as the motor is capable of making twice that amount.

Andrew

I found a good thread with pictures of Dave's Tr30r





Here:

http://www.evowned.com/forums/showthread.php?p=94647