Thing is I have never read or heard of a single warranty claim being knocked back because of a VAP tune.

 

Probably because the VAP tune hasn’t grenaded any engines yet.

 

Hey folks, I was speaking with another member and told him I knew 2 people that may be able to sort this out., I was hoping that maybe you and @OzXFR can comment?
Speaking to another tune shop about the VAP pulley they said this......

I suspect you may be referring to the velocity lower pulley. What we sell is the upper supercharger pulley. We do not recommend the lower pulley for several reasons. The main reasons is that it will not add more than 2lbs of peak boost. This is becauseyour supercharger will physically max out at 2 additional lbs of boost. The lower pulleys are generally rated at 4-5 lbs and while you will get this boost increase before you reach peak levels, you will not get more than 2lbs at peak levels. The problems isthat you will be spinning the supercharger faster than the manufacturer intended (since you are trying to get more peak boost than they allow) and as a result you will get significant heat soak and an eventual loss in performance. I know this is very technicalso if you like I can better explain in a phone conversation.

What do you guys think, Is there validity to this?

 

Lance (Unhingd) is the most fluent in this, but I don't think this is entirely accurate. He's got both upper and lower pulleys and by my recollection of his report, this is a little past the optimum at high rpm, but he's got enough dyno time and actual miles to give an accurate picture. I thin that lower pulley only on the V6, plus a tune that will not throw codes at the higher boost, will give spectacular results. I've only got the VAP tune, so take that for what it's worth. I eventually will get the lower pulley based on what I've heard here, but my time and means are not unlimited, by any means.

 

Sounds like marketing BS to me.
Both a smaller upper pulley and a larger lower pulley do the same thing - spin the SC faster to produce more boost - and I for one don't see how the upper pulley is "better" than the lower pulley.
I have the lower pulley on my V6 because as Lance (Unhingd) explains the stock V6 upper pulley is already close to as small as you can go and the slightly smaller tune pulley makes only a little difference while the larger lower pulley makes a much bigger difference. The other thing which swayed me to the lower pulley was the relative ease of fitment - bolt off bolt on and can be changed back - whereas it seems that without a Unicorn puller tool you can't get the stock upper pulley off without destroying it.

 

WOW, I would love to know where you got that.

Both pulleys swapped will result in overdriving the supercharger past the max limit allowed by Eaton. (20,000RPM for the 1320 (V6) and 18,000 for the 1900 (V8)

Thinking that simply spinning a supercharger faster equals more boost and more performance is incorrect in many ways.

First of all the efficiency drops, secondly.... passive crank losses due to higher power needed to spin faster and lastly, thermal considerations.

I love it when someone copies and tweaks things they read elsewhere...

There is a point where a larger supercharger is needed...

 

Gotcha, i think. What would the max be for what the VAP lower pulley/tune?

 

I could be wrong, and won't know until i speak with him in person, but I think he's suggesting that the supercharged pulley, although producing less boost and less power is a better choice as you will.have issues if you are overusing the superchargef vis heat soak or whatever?

 

I can only speak specifically to the V6.
1. Adding both upper and lower pulleys will indeed drive the SC to excessive speeds pushing the SC beyond adiabatic efficiency. I will be reverting to the OEM upper pulley as soon as I find one. ( Mine was destroyed when it was removed)
2. There’s little point in installing the upper pulley as it increases SC speed by a mere 2.5% on the V6. (60.5mm v 62mm OEM). Bigger gains are had on the V8 because that OEM pulley is 66mm.
3. The lower pulley is good for an 11.8% SC speed gain.
4. As the upper pulley provides a minor increase in boost (~1-1.5 psi), a tune is not required to avoid codes being thrown. However, the lower pulley will build an additional 4-5 psi of boost not anticipated or mapped in the OEM tune and will throw a code. The tuner has to develop a map to cover all the boost levels that will be encountered by the engine. The OEM tune will handle up to about 16psi. My peak boost is right at 20psi.
5. The upper pulley and tune will get you to about 425hp/375lb-ft. (Tune alone~416hp) The lower pulley/tune will get you to 450hp/425lb-ft.

 

Lots of great information here, thanks @Unhingd .
What do you think the torque was before you did the pulley, when you were just using the tune?
Also, once the pulley and tune are added, I think it would be fair to say that the supercharger is at its maximum, would 'heat soak' be a relevant variable?

 

I believe that came in under 350. Note that the S only has 7 more lb-ft of torque than the base V6. You need to get more air to the engine at lower rpm to build a lot more torque and a tune alone won’t do that.

Yes, heat soak is an issue particularly when the car is at standstill on a dyno. We would see a 10-15 hp loss after 3 or more consecutive runs.

 

I'm considering the VAP tune but with the coolant loss issues I'm experiencing it's hard to move forward. Most tuned cars are lower mileage, mine is approaching 60K, outlet pipe, oil cooler and thermostat housing need to be replaced due to leaks. Weak point on these cars is starting to show at higher mileage..

 

In your opinion, is there any way to circumvent these issues?
I use my car as a daily with some spirited every so often. Would heat be more an issue from driving hard on a track or will the heat just naturally occur as a byproduct of the added stress, and therby unavoidable?

 

Absolutely not an issue on the street. As long as the tunes do not compromise safe a/f mixtures or calculated detonation limits in favor of power, there is no more stress on these engines when at comparable power output to the OEM tune and boost. The heat issue also not an issue on the street as full throttle acceleration is generally not an immediate sequential circumstance, nor is constant full throttle operation. If mine were a track car, I would indeed be adding additional cooling capacity to the intercooler to maximize availability of full power. But then, I would also be gutting the car to strip off another 500+ pounds.

 

I do wonder why a two seater all aluminum roadster would weigh 3,900 pounds. Maybe it's all the electric motors under the seats. Ha

 

4 airbags and deployment systems, 12 speakers and accompanying amps, 80 lb seats, glass panel roof, rear hatch motor, 30% excess engine block weight (V6), wheels and brakes designed by a boat anchor engineer.

 

That's very helpful @Unhingd thank you. I had heard of the heat issue with the AJ-133 but it not being an issue with the v6.
Unrelated, but do you find that the pulley has an impact on the throttle responsiveness, in that it makes it more sensitive?

 

My tune was perhaps one of the first issued by VAP and offered a smooth throttle response until I installed the lower pulley. The throttle response then became so notchy and sensitive as to be quite unpleasant and difficult to lay down the power smoothly. They have since fully resolved the issue and the throttle response is now very smooth and predictable. Even in dynamic mode, very smooth and predictable, but power is applied more quickly in the top half of the throttle range.

 

Did you ever get around to logging any performance data?

 

Only substantial testing on an axle mount chassis dyno (Dynapack).