How much boost did you lose with long tubes?

[ExpatMedic]

Figured I'd start a new thread and ask this question directly.

I am considering an upper/lower pulley change, which will really start pushing the limits of how much boost pressure we can throw at these engines, so I am also consider some longtubes to help alleviate some of the pressure. In order for my math to be correct, I need to get an idea of how much boost the 3v loses when you go to LT's.

I'm currently running 10.74lbs at peak with a stock exhaust system, including cats. Well, I have an axle back too..which doesnt account to much. Is a full 2psi worth of loss realistic?

 

[95ragtop]

Why not get the long tubes on and see what the car produces then buy whatever pulley you need, that way there is no guessing.

 

[ExpatMedic]

Because there is a severe lack of pulley sizes with the blower setup I have.

3.0 is the largest upper pulley available that makes sense..the next jump is to a 3.5. No one seems to make a pulley between 3.0 and 3.5 that will work for the dual belt 8 rib TVS. 3.2 would probably be ideal for the way my car sits, w/o exhaust mods...but, no dice. So, it will need to be the 3.0 and a way to relieve pressure.

If there wasn't such a lack of pulley selections, this would be a lot easier.

 

[Full_Tilt]

Generally the power made by the headers should be much more than the power lost from the small drop in boost pressure.
Its hard to say exactly how much it will drop, their are lots of variables, but in the past Ive only ever seen a few psi lost when going to a large primary long tube header.

 

[ExpatMedic]

Well, you dont lose power from the loss of boost in such a situation, but thats a different topic.

A few PSI of loss in pressure (boost) would be outstanding, as I'm only looking to add a little over 2PSI worth of boost to the engine. If I could achieve a full 2psi worth of 'loss', then I'd be a happy camper.

 

[95ragtop]

Shitty situation then. In your other thread you asked about installing long tubes, they aren't that bad, I did them in a baracks parking lot. Are long tubes and cams an option or is that to much money?

 

[ExpatMedic]

Shitty situation then. In your other thread you asked about installing long tubes, they aren't that bad, I did them in a baracks parking lot. Are long tubes and cams an option or is that to much money?

Did you have to lift the motor to do it? How many hours do you think you invested and which ones did ya go with, if you dont mind me asking?

I wouldn't say it's too much money, I just don't think its the most cost effective way, especially in time spent. Swapping out some pulleys is a little cheaper than cams (not much, honestly) and a whole lot easier.

The lower pulley is $500 by itself, another $130 for the upper pulley..so not far off from the cost of cams. Probably have to buy a couple tools if I did cams, such as the wedge.

I'm also thinking boost would give me 'better' power than either NSR cams or LT's.

 

[95ragtop]

I didn't have to lift the motor, but I did use a jack to support it while I unbolted the motor mounts. Hours invested I can't say for sure, it took me 2 weekends though because of little things going wrong: didn't know I needed 2 jacks to do this, so I had to run to autozone, thought I could use the stocks header bolts (wrong), I'm sure I had to make a run to buy an extension or wrench at one point. If I did it again in a garage with light, it could be done in 1 day. I went with JBA, this was back in 08 and they were a good price, fit well.

Edit: Reason for using 2 jacks was I didn't feel comfortable only using a jack stand with the height I had to raise the car to get the long tube to fit, so I used the jack and jack stand for one side and then one jack for the motor.

 

[weather man]

Just remember that lowering the boost with long tubes makes more power. You are making the pump (engine) more efficient. If I remember, you are on the stock bottom end. If this is your DD, just make sure you have a plan, if she lets go.

 

[ExpatMedic]

Just remember that lowering the boost with long tubes makes more power. You are making the pump (engine) more efficient. If I remember, you are on the stock bottom end. If this is your DD, just make sure you have a plan, if she lets go.

All it takes is money, right?

Hopefully that's not in my future. The thought is that ~460rwhp (uncorrected) or so will keep me safe. I'm thinking ~30rwhp from a little over 2lbs of boost and then whatever LTs add..I really can't see them adding more than 15rwhp?

I'm at 420-430rwhp (uncorrected) right now with 11.8-11.9 AFR's and 25* of timing. An additional 45rwhp should keep me in the 465-475rwhp range, which I could back down a bit by pulling some timing and going a little richer.

Of course, anything can happen..spose thats the risk we take.

 

[95ragtop]

Can you mix and match the upper and lower pulleys? ie: use a smaller lower with the 3.0 upper? I've seen 15-20 with NSR cams and 30 with VSR cams. Which ones were you looking at?

 

[ExpatMedic]

Can you mix and match the upper and lower pulleys? ie: use a smaller lower with the 3.0 upper? I've seen 15-20 with NSR cams and 30 with VSR cams. Which ones were you looking at?

Yea, Roush has 2 lower pulleys and I am running the smallest lower pulley and the smallest upper pulley possible.

I will be going with the larger Roush lower pulley (7.22" vs 5.66") and will definitely have to go up a few sized on the upper pulley...3.0" in this case.

I was looking at the NSR cams, detroit rockers and Comp Cams.

 

[weather man]

Some guys live in that HP range a long time and some not so long. Obviously, the harder driven with strip time are pushing harder than pure street use. You have researched, so you know the deal. Nothing wrong with pushing the motor with your eyes wide open.

 

[95ragtop]

Found a thread that might help you out, looks like you can get custom pulleys made.

http://www.moddedmustangs.com/forums/2005-2010/185547-roush-tvs-2300-dual-belt-phase-2-a.html

 

[ExpatMedic]

Found a thread that might help you out, looks like you can get custom pulleys made.

http://www.moddedmustangs.com/forums/2005-2010/185547-roush-tvs-2300-dual-belt-phase-2-a.html

Unfortunately, Carmen stopped making pulleys some time ago.

 

[Memphis 05]

Just remember that lowering the boost with long tubes makes more power. You are making the pump (engine) more efficient. If I remember, you are on the stock bottom end. If this is your DD, just make sure you have a plan, if she lets go.

2nd this..the engine will flow better resulting in better power.

you may loose boost but make more power easily, therefor making your goals easier to achieve. Adding cams and a good tune and you should be be at your goals. plus the combo of the cams and long tubes will sound better.

I have the detroit rocks w/LT... love it! Old school feel with great idling properties. well worth it......

good luck

 

[Vapour Trails]

You are focused on boost pressure when you should be focused on power, or more specifically torque. If long tubes result in more power, there is more torque somewhere in the rpm range and that is what will kill your engine, regardless of what the new boost pressure is.

Really, on a stock 4.6L you should just leave your current setup alone unless you want to buy a forged short block.