Question: AVNT4094/vs cheetah ?
- Thread starter slowlmm
- Start date
X2.
I have been tossing the vnt vs HTT idea around for awhile. Now I am set on the vnt with plans to twin, just not 100% sure which vnt to use yet...
For what it's worth... i have tried a couple different VNT chargers on my truck - which is twinned - so my results will be different than alot of others.
Currently i have the Danville stage 2 (68 mm compressor wheel).
It's a pretty turbo, and i like both how it sounds and how it performs in combination with the (so far) 2 different turbos i've had feeding it from the twin setup.
What i've noticed between the Garrett 3794 and the Danville stage 2 (both turbos i've had on in the twin config) is that of drive pressure and overall boost.
I think many have found that the new Stage 1 Garrett AVNT 3794 fell a little short of what they were hoping for, and my opinion now is that is mostly due to the exhaust side - though i know the compressor wheel wasn't a full 94 wheel either (was trimmed down i was told).
Regardless, my experience with it was, with identical tuning, that i dropped over 10 PSI of drive pressure when replacing it with the Danville turbo, and that was with the exact same tuning being used. Now being twinned changes things, however, my experience was better performance, quicker spool, and (though some might not like it) alot more whistle. I am told the noise is comparable to the Cheetah - but i like it.
I have NOT tried the 4094 AVNT on my truck - and don't think i will be able to (no $$$). I've seen the compressor and turbine maps for both AVNT 3794 and AVNT4094 (Stage 2) - and though i had to learn alot to be able to make somewhat sense of them, It looks as though the AVNT 4094 will indeed flow more on the compressor side (+/- 12-15 lbs/min. if memory serves) is seems all these VVT turbos suffer from the turbine side restrictions. I'm not saying that my current VVT flows more on the turbine side at all - i would still like to see further improvements to the flow on it as well - but going from Garretts own charts - I didn't see where the turbine side improved much from the 3794 to the 4094.
I do wish I could compare these two chargers side by side - swap out the Danville for the 4094 AVNT to try. I believe Drive Pressure correlates directly to higher EGT - and i dont believe i'd see much reduction, if any between the two in terms of drive pressure. I'd love to find out though and report on gains / losses too. But, i just don't have any more money to experiment with the setup. I have a ton of logs from both chargers, and how much harder the AVNT 3794 was working with the identical tune under load - but the logs alone don't paint the whole picture, and i don't have the other necessary info in the log (Drive pressure / EGTs).
I'd like to lower drive pressures even further as I believe (as do lots of others) that a couple psi less drive pressure can be alot better than a couple more psi boost for better performance. Lots of theories on that - but my own experience has shown it to be true so far.
Currently i have the Danville stage 2 (68 mm compressor wheel).
It's a pretty turbo, and i like both how it sounds and how it performs in combination with the (so far) 2 different turbos i've had feeding it from the twin setup.
What i've noticed between the Garrett 3794 and the Danville stage 2 (both turbos i've had on in the twin config) is that of drive pressure and overall boost.
I think many have found that the new Stage 1 Garrett AVNT 3794 fell a little short of what they were hoping for, and my opinion now is that is mostly due to the exhaust side - though i know the compressor wheel wasn't a full 94 wheel either (was trimmed down i was told).
Regardless, my experience with it was, with identical tuning, that i dropped over 10 PSI of drive pressure when replacing it with the Danville turbo, and that was with the exact same tuning being used. Now being twinned changes things, however, my experience was better performance, quicker spool, and (though some might not like it) alot more whistle. I am told the noise is comparable to the Cheetah - but i like it.
I have NOT tried the 4094 AVNT on my truck - and don't think i will be able to (no $$$). I've seen the compressor and turbine maps for both AVNT 3794 and AVNT4094 (Stage 2) - and though i had to learn alot to be able to make somewhat sense of them, It looks as though the AVNT 4094 will indeed flow more on the compressor side (+/- 12-15 lbs/min. if memory serves) is seems all these VVT turbos suffer from the turbine side restrictions. I'm not saying that my current VVT flows more on the turbine side at all - i would still like to see further improvements to the flow on it as well - but going from Garretts own charts - I didn't see where the turbine side improved much from the 3794 to the 4094.
I do wish I could compare these two chargers side by side - swap out the Danville for the 4094 AVNT to try. I believe Drive Pressure correlates directly to higher EGT - and i dont believe i'd see much reduction, if any between the two in terms of drive pressure. I'd love to find out though and report on gains / losses too. But, i just don't have any more money to experiment with the setup. I have a ton of logs from both chargers, and how much harder the AVNT 3794 was working with the identical tune under load - but the logs alone don't paint the whole picture, and i don't have the other necessary info in the log (Drive pressure / EGTs).
I'd like to lower drive pressures even further as I believe (as do lots of others) that a couple psi less drive pressure can be alot better than a couple more psi boost for better performance. Lots of theories on that - but my own experience has shown it to be true so far.
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I remember that video.
Have you been able to duplicate the results on another truck with the same combination?
I agree, I tried everything under the sun to make the PPE GT4094R kit work correctly, like different turbine housing with and with out wastegate with no really change in egt's vs. performance. It was one of the hottest running turbo's I have ever seen. After tons of testing I finally found the answer but it was expensive as hell and I have to figure out how to make it more cost effective for the end user. It turned out to be one of the most fun turbo's that I have ever driven. It made 680hp and 1450ftlbs(at 2000-2500rpms) on a built 6.6L DMax and the egt's do not go north of 1400degrees!
The 4094VA works very nicely but still is not perfect. The compressor cover hits the intake clam on the driver's side so you have to grind it so the charger will fit in the hole. It doesn't look stock at all. We have been running it for a while now on Larry's truck and have mixed emotions about it. If you never drove a truck with my version than it is a great charger and you will love it. Larry however had ran a year on my 68mm STG2 and when I switched out the charger for the Garrett 4094va he wasn't as happy with it. The truck smoked more than before with higher egt's across the board and the power was about the same(600rwhp on the big tune) but less tip in power during in town driving. He is used to it now so it doesn't bother him. Has the same sound as mine. For the price I think mine is still a better deal with more bang for the buck, jmpo. A 4202VA would be nice...:spit:
PS- Brayden, I am coming for that quarter mile time...
I did 12.19 in ECSB LLY single pumped with my 65mm STG2 2.6, I think I can get to your time after sled pulling is over...
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Thanks for the info Mark.
The 4094VA is alot better than the 3794va. The 3794va was pretty much a flop and the 4094va will do much better just not enough for me to give up on what I am doing.
Just curious but earlier on I read that the AVNT chargers aren't for the high horsepower junkies. Did I read right?
Nick
Nick
4094R uses a High Pressure Drive Turbine wheel. It takes heat and pressure to make it spin. It is designed that way. It sucks for use on a diesel truck. A GT4294 spools much better with a larger turbine wheel driving the same comp wheel. But you already know that.
I wouldn't say they are overrated, they will take a lot more of a beating than a journal bearing one, and they will spool faster.
X2, I am a HUGE fan of the ball bearing chargers and have had great success with them except for the 4094R. You are exactly right John but the problem is that the turbine doesn't last too long in the high heat, it errodes and the problem gets worse. It is just miss matched. As far as AVNT's for high horsepower, they will make enough to break stuff so they are good in my book.
What is the considered longevity of a vvt like yours as opposed to say a journal/ball bearing? You can't rebuild a ball bearing correct but a journal you can? I don't really understand why...
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It is more that the ball bearing can be overspeed without to much worry but a journal bearing will fail fast if overspeed. If you have the tuning right on an AVNT it should last a long time. I have a customer that has been competitively sled pulling on one of my 2.5 STG1 for two years now without issue. Larry's original stg1 2.5(was the first one I built way back when) is on it's third truck now without being touched. Have a customer with the Gt4094R PPE kit and it lasted one pulling season and eat the turbine inducer tips. Had a customer pull for two years straight(over 100 hooks and tons of street driving in between) on one of my LB7 2.6 kits at well north of 600hp (dynoed 660rwhp) and it was one of the most competitive trucks around here in the 2.6 class last year. Took a built motor and a 200hp shot of nitrous to blow it up( the charger that is) because there was not enough wastegate flow to compesate for the spray, shit happens. This is the only one of these that has failed todate. When we built the motor, I took the charger apart to see how it looked after two years of pulling and it was still like brand new inside. I was amazed since I know how hard we beat on it for two years. Just my personal experiences here, take them for what they are worth.
Our race truck has the GT4094R in it and egts were high along with turbo lag. Just installed a set of PPE manifolds and up pipes and it came alive! Not even the same truck! Great response and egts dropped about 100 degrees. I just installed the 4094vvt in my truck tonight and I'm throwing all kinds of codes. i have efilive but I'm not a tune builder i just tinker. If anyone can help me with the proper settings for this turbo I would greatly appreciate it. It does whistle like crazy!