VNT upgrades.

[maddmannda]

I want to collect VNT info and experience in an effort to dispel the misinformation of these awesome turbos and preserve the dwindling use of VNT turbos.

Many VNT vehicles were originally purchased as collectors' items and were only driven sparingly. Sporadic use is likely the main cause of the vane sticking REPUTATION. If any car needed the carbon blown out, its the VNT!!! Those who regularly drive their VNT report few issues w/ the VNT.

I plan to try numerous upgrades and document my findings. I have read everything I could find pertaining to the VNT. I believe the Intercooler (IC) is the achilles heel of the VNT setup. The CSX-VNT has a very restrictive IC and the '90 VNT IC is even more restrictive. I theorize a decent FMIC will greatly reduce other VNT issues including boost creep plus allow an upgrade to VNT-28 or bigger.

I welcome all input!!

[2.216VTurbo]

Dwindling use of VNT's? I don't think so, I think they are pretty common with manufacturers today. My last DD an '06 VW Toaureg V10 TT TDI used two Garretts. I don't recall the exact number but they were made in France and used a VNT 17 compressor wheel. Literally a quarter placed of the inducer would cover up the wheel they are so tiny! One Achilles heel that platform suffered in relation to the turbo's that the controller boxes would go out. The dealers initially replaced the turbo as a unit when a low boost issue was encountered, but then so many failures occurred that they dug into them further and figured out that it was a VNT Controller issue and VAG didn't have to spend the money on an entire replacement turbo assembly. What they DID have to do for every replacement is drop the entire drivetrain out for turbo/controller replacement:wow1: Interesting maybe to note (and maybe the only info that helps this thread;)) is that the VNT control box has 6 wires going into it. Shelby accomplished it with a dual port controller and a couple solenoids:amen: I'm interested in this 28 upgrade you speak of, I've seen that done years ago by TEC but not sure if advancements in the last 15 years have come into play? Is there any upgrade or work done to the turbine side on the upgrade you're exploring?

[cordes]

With the stock VNT turbo I think it's an exercise in chasing one's tail to upgrade the hard parts. Especially the exhaust. I had one of the TEC turbos on my CSX along with a more free flowing muffler, ported head, two piece intake, and exhaust. The boost was uncontrollable over 4K regardless of what I did to it.

[Oggie Fisher]

If you haven’t already check out Gary Donovan’s The Dodge Garage website, specifically the “SDML Posts”, and “7 Pages of information from Mr. 5DIGITS” sections. There are lots of good information on the VNT.

The engineers at SDAC-22 spoke about the VNT as well. The nail in the coffin, so to speak, for the VNT above all else was the 2.5 T1 was able to produce the same numbers, cost less to produce and was a simpler design. I recall them also saying that while initially the exhaust and muffler was relied upon to regulate max boost they modified the code to use regulate vanes to prevent overboost as well. I have to check my notes to see if there was anything else in there that isn’t mentioned in on Gary’s pages.

To confirm your thoughts on the intercooler, I believe there is thread out there that discussed recommended installing a Super 60 intercooler on a VNT, and that even an upgrade to a stock T2 IC is beneficial.

[maddmannda]

With the stock VNT turbo I think it's an exercise in chasing one's tail to upgrade the hard parts. Especially the exhaust. I had one of the TEC turbos on my CSX along with a more free flowing muffler, ported head, two piece intake, and exhaust. The boost was uncontrollable over 4K regardless of what I did to it.

What IC were you using?

[maddmannda]

Dwindling use of VNT's? I don't think so, I think they are pretty common with manufacturers today.

Sorry, you inferred I meant global VNT usage, I am referring to the dwindling use on '89 CSX & '90 Turbo MoPars.

[maddmannda]

If you haven’t already check out Gary Donovan’s The Dodge Garage website, specifically the “SDML Posts”, and “7 Pages of information from Mr. 5DIGITS” sections. There are lots of good information on the VNT.

Yes, I believe I have read all of those pages, but I will look again.


The engineers at SDAC-22 spoke about the VNT as well. The nail in the coffin, so to speak, for the VNT above all else was the 2.5 T1 was able to produce the same numbers, cost less to produce and was a simpler design. I recall them also saying that while initially the exhaust and muffler was relied upon to regulate max boost they modified the code to use regulate vanes to prevent overboost as well. I have to check my notes to see if there was anything else in there that isn’t mentioned in on Gary’s pages.

Thanks, Do you have more info on the modified code to control overboost?

[1BADVAN]

I believe that Member TurboShelbys has been running 13's with his 89 CSX and a 3 inch exhaust, probably one of the few people who has pushed it that far, claims to be the fastest

[1BADVAN]

http://www.turbo-mopar.com/forums/showthread.php?t=63889

[cordes]

What IC were you using?

Stock TII IC.

[Vigo]

I am still planning to build a modified VNT setup, so i am all for this thread.

However, i disagree that the stock intercooler is the main sticking point. I believe that the main reason VNTs are not modified or are swapped out for something more easily modified is due to the lack of adequate boost control from the vanes only. In my opinion, the thing the VNT needs most is a wastegate. Once it has that and can be turned up slowly and tuned for carefully, its limits can be explored more often, such as Turboshelbys did with his 13-second CSX. Noone is really taking the chance of installing an upgraded compressor that could boost spike into the 20s or even 30s psi without having solid boost control, and the lack of that is what keeps VNTs either stock, or on the shelf collecting dust.

[cordes]

I am still planning to build a modified VNT setup, so i am all for this thread.

However, i disagree that the stock intercooler is the main sticking point. I believe that the main reason VNTs are not modified or are swapped out for something more easily modified is due to the lack of adequate boost control from the vanes only. In my opinion, the thing the VNT needs most is a wastegate. Once it has that and be turned up slowly and tuned for carefully, its limits can be explored more often, such as Turboshelbys did with his 13-second CSX. Noone is really taking the chance of installing an upgraded compressor that could boost spike into the 20s or even 30s psi without having solid boost control, and the lack of that is what keeps VNTs either stock, or on the shelf collecting dust.

I'm convinced that a VNT with an external WG would be an incredible combination for autocross or track days. You'd still have to keep the boost at 18-20PSI to keep the turbo alive, but it would be fun.

[turboshelbys]

You can control boost on a VNT quite easily with a pair or even a single mbc.

[turboshelbys]

What IC were you using?

I am using the stock vnt I/C, 215.8whp 253.1wtrq(248.1 flyHP 291flyTrq) at 16psi.

[maddmannda]

I am using the stock vnt I/C, 215.8whp 253.1wtrq(248.1 flyHP 291flyTrq) at 16psi.

But your 13-sec passes were with the FMIC, correct??

[maddmannda]

I am still planning to build a modified VNT setup, so i am all for this thread.

However, i disagree that the stock intercooler is the main sticking point. I believe that the main reason VNTs are not modified or are swapped out for something more easily modified is due to the lack of adequate boost control from the vanes only. In my opinion, the thing the VNT needs most is a wastegate. Once it has that and be turned up slowly and tuned for carefully, its limits can be explored more often, such as Turboshelbys did with his 13-second CSX. Noone is really taking the chance of installing an upgraded compressor that could boost spike into the 20s or even 30s psi without having solid boost control, and the lack of that is what keeps VNTs either stock, or on the shelf collecting dust.

You may be correct, but I noticed the common difference of those who ran the best times, like Turboshelbys, was an upgraded IC. An upgrade to the compressor side of the VNT may indeed require a wastegate, but I believe a good FMIC will greatly reduce the boost issues on a near stock VNT.

[maddmannda]

I'm convinced that a VNT with an external WG would be an incredible combination for autocross or track days. You'd still have to keep the boost at 18-20PSI to keep the turbo alive, but it would be fun.

Me too!! I am anxious to see what can be done w/ the VNT!!!

I've always been the guy who bucks the 'NORM'!! I had a '69 AMX when no one knew what they were!!! In '81-82 people at gas stations thought it was a NEW car!!
I ran a 360 in my 'Cuda back when the only small block MoPar was a 340. I took a beautiful '78 Volare Super Coupe I had just purchased, to the MoPar Nats in '86, it went mostly ignored!! At LSU, I drove an '83 Spirit GT 4.2L I6 5 speed (AMC used the T-5 before Ford or GM). Preferred my '73 Charger SE with gold cloth bench bucket & column shift over a Charger Rallye w/ bulge hood & bucket seats w/ floor shift!! Drag raced & Auto-crossed my company issued '91 Caravan SE (which I paid out-of-pocket to upgrade to the V6, add HD brakes & suspension & gauge package!!)

[turboshelbys]

But your 13-sec passes were with the FMIC, correct??

ran my best 13.6 and 13.7 with the crappy tube and fin i/c, but ran tons of 13.8's with the stocker. All runs were with the stock cam and on old bfg drag radials as well. keep in mind my times were also getting better the more I went to the track. I didn't "feel" the i/c swap netted me much if anything.

[turboshelbys]

You may be correct, but I noticed the common difference of those who ran the best times, like Turboshelbys, was an upgraded IC. An upgrade to the compressor side of the VNT may indeed require a wastegate, but I believe a good FMIC will greatly reduce the boost issues on a near stock VNT.

One thing to note, we have found the vnt setup gets extremely hot once the boost starts to come up past factory spec. egt's are always a concern when "modifying" the vnt.

[glhs875]

I am still planning to build a modified VNT setup, so i am all for this thread.

However, i disagree that the stock intercooler is the main sticking point. I believe that the main reason VNTs are not modified or are swapped out for something more easily modified is due to the lack of adequate boost control from the vanes only. In my opinion, the thing the VNT needs most is a wastegate. Once it has that and can be turned up slowly and tuned for carefully, its limits can be explored more often, such as Turboshelbys did with his 13-second CSX. Noone is really taking the chance of installing an upgraded compressor that could boost spike into the 20s or even 30s psi without having solid boost control, and the lack of that is what keeps VNTs either stock, or on the shelf collecting dust.

Very good points! I agree!

[maddmannda]

ran my best 13.6 and 13.7 with the crappy tube and fin i/c, but ran tons of 13.8's with the stocker. All runs were with the stock cam and on old bfg drag radials as well. keep in mind my times were also getting better the more I went to the track. I didn't "feel" the i/c swap netted me much if anything.

Which ebay I/C were you running?

[maddmannda]

One thing to note, we have found the vnt setup gets extremely hot once the boost starts to come up past factory spec. egt's are always a concern when "modifying" the vnt.

Do you think a good FMIC would help with the high temps? Is there an FMIC that other TM guys have used w/ success?

[tryingbe]

I have a FMIC setup for sale, it would work perfect for you. I used the same style intercooler to make 290whp on my GLH on E85 on my 2.2L. Ran a 13.2 at 110mph

http://www.turbo-mopar.com/forums/showthread.php?80521-FMIC-setup-BOV-ADJ-cam-pulley-pt-lifters-muffler-oil-catch-can-starters-etc&highlight=

[turboshelbys]

Which ebay I/C were you running?

http://i1380.photobucket.com/albums/ah170/turboshelbys/047_zps47g25ze1.jpg

While it flowed very nice, I do not believe it cooled worth a tinkers damn.

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Do you think a good FMIC would help with the high temps? Is there an FMIC that other TM guys have used w/ success?

It would help with intake temps and density, but not with egt's

I am going to be installing an custom I/C, that I ran on my Shelby Lancer for about 10 years, and see if there is any gain there. It's two talon i/cs. Then I'll be installing an mbc to turn up the boost slightly, looking for 19ish. Once that is done I am going to install an Adj cam gear and dial in the custom cam. Hoping I can get this done soon, but my upcoming move is soaking all my time.

http://i1380.photobucket.com/albums/ah170/turboshelbys/PART_1464275360497_zpsqlv5kcfq.jpeg

[going4speed]

crazy question. would a fmic and w/c intercooler compounded together be worth anything? I have not seen that done...probably for a reason..haha:confused:

[turboshelbys]

crazy question. would a fmic and w/c intercooler compounded together be worth anything? I have not seen that done...probably for a reason..haha:confused:

combining the two would create a lot of lag in the system and wouldn't produce any favorable results i would think.

find a good flowing/cooling bar and plate i/c use as little plumbing and bends as possible. if you are really worried about intake temps and heat soak add a meth kit and i/c sprayer.

on my lancer i run a water to air and spray meth. i also filled the i/c system with 50/50 meth/water. seems to cool well and if there is ever a leak my motor will inhale something that will burn vs using a coolant mix.

matching the right components to your specific system is important, "no one size fits all"

[maddmannda]

I have a FMIC setup for sale, it would work perfect for you. I used the same style intercooler to make 290whp on my GLH on E85 on my 2.2L. Ran a 13.2 at 110mph

http://www.turbo-mopar.com/forums/showthread.php?80521-FMIC-setup-BOV-ADJ-cam-pulley-pt-lifters-muffler-oil-catch-can-starters-etc&highlight=

I was looking at a FMIC like that, Spearco knock-off? What brand?