Turbo Dodge Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
453 Posts
Discussion Starter #1
I am planing my money and would like to know what REAL results are to be had over the 2.5 that came on my car (I belive). I am buying the DP and exhaust, And soon a header from the guy in dayton. but is the swingvalve worth it?
 

·
Registered
Joined
·
4,693 Posts
I recently dynoed my Shelby Lancer and my brother dynoed his '89 Lebaron GTS.

Both cars are TII, with manual trans, and similar mods and same boost level (14 psi). The only differences between our setups:

SL has 3" TU/FWDP exhaust (including TU swingvalve); GTS has 2.5" JRB exhaust/stock swingvalve
SL has 2 piece intake, GTS has 1 piece intake

We dynoed both cars one right after the other. The Shelby Lancer made an average of 20 WHP and 15 WTQ over the GTS along the entire curve!
 

·
Registered
Joined
·
789 Posts
iTurbo said:
I recently dynoed my Shelby Lancer and my brother dynoed his '89 Lebaron GTS.

Both cars are TII, with manual trans, and similar mods and same boost level (14 psi). The only differences between our setups:

SL has 3" TU/FWDP exhaust (including TU swingvalve); GTS has 2.5" JRB exhaust/stock swingvalve
SL has 2 piece intake, GTS has 1 piece intake

We dynoed both cars one right after the other. The Shelby Lancer made an average of 20 WHP and 15 WTQ over the GTS along the entire curve!

This doesn't really prove anything on how much h.p. the 3" makes over the 2.5". If you both dynoed the same, then you installed the 3" and then you both dynoed again would be a better test. Too many variables in the above statement. Even installing the 3" and then adjusting making a retune doesn't show a accurate test. Maybe the tune wasn't up to par to begin with and then you added the part and then tuned it. Tune it to a a/f ratio and and then install the part and then retune it to the a/f ratio would be more accurate.
Just my .02 worth.
 

·
Registered
Joined
·
4,693 Posts
MVaughn said:
This doesn't really prove anything on how much h.p. the 3" makes over the 2.5". If you both dynoed the same, then you installed the 3" and then you both dynoed again would be a better test. Too many variables in the above statement. Even installing the 3" and then adjusting making a retune doesn't show a accurate test. Maybe the tune wasn't up to par to begin with and then you added the part and then tuned it. Tune it to a a/f ratio and and then install the part and then retune it to the a/f ratio would be more accurate.
Just my .02 worth.
I agree and I wouldn't go so far as to say the 20 HP my SL had over the GTS was all due to the swingvalve differences (3" vs 2.5"), but it was the most notable difference between the two cars. A back-to-back test on the same vehicle would be more meaningful, but that would be very hard to do unless you had all day to mess around on a dyno with wideband.

I think another informative test would be to dyno a vehicle with a 2.5" swingvalve and exhaust system, and then install a 3" swingvalve and exhaust system and dyno it again with no other changes. Most people that buy the 3" swingvalve also upgrade the rest of the exhaust system to match it and don't have the ability to retune with every change made to the car.

I will try to scan the dyno sheets and post them here soon. The curves look almost identical, except the SL is 15-20 HP above the GTS at all points along the graph. With both cars pushing 14 psi on mostly stock TII setups, the SL made 196 WHP/242 WTQ while the GTS made 178 WHP/218 WTQ. :confused: The A/F on both cars nosedived off-the-scale rich as soon as full boost was reached.
 

·
Administrator
Joined
·
10,119 Posts
I bought one, lot faster spool up and little top end. The TU dyno is accurate. The bad part is the O2 bung. They make them thick to pull the sensor out of the path on a 2.5" turbonetics SV. Well this may help flow some on a 2.5 or 2.25, but on a 3" it is pointless. Then the exhaust pressure at the SV is lowered allot, whole reason you buy it, but then sensor gets hosed. Mine and 2 others here run worse around town and at idle. I am cutting the bung down to get the O2 as far out into the path as stock or better. Regardless a TU 3" SV is a must as far as I'm conserned, once you go 3" it's really hard to go back.
 

·
Registered
Joined
·
1,744 Posts
The Pope said:
I am cutting the bung down to get the O2 as far out into the path as stock or better.
Good idea! I would never have thought of that. I've had chronic idle problems :bang head
 

·
Registered
Joined
·
4,693 Posts
I have the 3" TU swingvalve on my Omni and Lancer and I've never had problems. It idles the same as ever before. Even the A/F gauge behaves just as it always did. I doubt the O2 bung location is your problem.
 

·
Administrator
Joined
·
10,119 Posts
iTurbo said:
I have the 3" TU swingvalve on my Omni and Lancer and I've never had problems. It idles the same as ever before. Even the A/F gauge behaves just as it always did. I doubt the O2 bung location is your problem.
my car had no other changes. Also I have no cat, straight through muffler and it's a shorty out the side exhaust. You run to the back of the car and through a turbo muffler and cat and the pressure in the SV is completely different than what is going on in mine. The difference is not huge, but it is noticable. On a 3" SV the O2 doesn't need to be pulled back anyway, it's not going to effect flow at all. As it is about half of the sensor is in the exhaust track. Doesn't matter it is an easy mod.
 

·
Registered
Joined
·
4,693 Posts
Actually, neither my Lancer or Omni have catylitic converters, and both have Dynomax Ultraflo mufflers which are straight-thru.
 

·
Registered
Joined
·
255 Posts
If I have 2.5" JRB exhaust on already, would there be any gain to be had if I put one on my garrett turbo? 91 shadow turbo ES 2.5

would it be worth the 100dollars more than the 2.5" costs? I need to buy one anyway since I will be converting my garret T1 to T2 status and it currently has a 2.25" swingvalve. so I guess the question is:

2.5" swing valve with 100bucks in my pocket
or
3" swing valve and whatever gain in performance

which should I choose?

Thanks Jake
 

·
Administrator
Joined
·
10,119 Posts
shadowjake said:
If I have 2.5" JRB exhaust on already, would there be any gain to be had if I put one on my garrett turbo? 91 shadow turbo ES 2.5

would it be worth the 100dollars more than the 2.5" costs? I need to buy one anyway since I will be converting my garret T1 to T2 status and it currently has a 2.25" swingvalve. so I guess the question is:

2.5" swing valve with 100bucks in my pocket
or
3" swing valve and whatever gain in performance

which should I choose?

Thanks Jake
3" if you are going to buy 3" exhaust too
 

·
Registered
Joined
·
2,216 Posts
shadowjake said:
If I have 2.5" JRB exhaust on already, would there be any gain to be had if I put one on my garrett turbo? 91 shadow turbo ES 2.5

would it be worth the 100dollars more than the 2.5" costs? I need to buy one anyway since I will be converting my garret T1 to T2 status and it currently has a 2.25" swingvalve. so I guess the question is:

2.5" swing valve with 100bucks in my pocket
or
3" swing valve and whatever gain in performance

which should I choose?

Thanks Jake
If you have stock exhaust, just use the 2.25" you have for now and upgrade the exhaust to 2.5" mandrel bent or 3" any kinda bend you can afford now and do a SV later. I say this cause p-body stock exhaust is only like 1.875" ID over the axle and the stock mufflers suck too... much more important and beneficial than a .25" or .75" bigger SV housing...

The smallest restriction needs to be addressed first!

I have used the stock 2.25" SV, Turbonetics 2.5" SV and now have a TU ceramic coated 3" SV.

My experiences:
Last fall on my Shelby Z, I went from the 2.5" Turbonetics to the 3" TU SV with that being the only mod except slight 2 degree angle modification to the end of my custom 3" downpipe to make it fit better with my header, I also thermal wrapped my downpipe at that time.

Other exhaust details:
Custom BadAssPerformance (I made it) Header, .63 A/R Stage 3 Turbine housing/wheel, custom (I made it) 3" downpipe which is just under 3" at the neck where the flange is, no cat, 3" mandrel bent straight back, dual 45 degree bends instead of factory 90's cause the gas tank was replaced with a 5-gallon cell and I had room, Dynomax race magnum 3" bullet muffler.

The results:
I have yet to dyno the car, but with the 2.5" and 3" both net the same 120mph 1/4 mile trap speeds.

The conclusion:
The least restriction is still the just under 3" necked portion of the downpipe, wich is larger than the 2.5" SV, but smaller than the 3" SV...

FWIW, my Shadow runs the Z's old exhaust which is muffler shop smooth bent (read: non-mandrel bent) 3" pipe with a race magnum oval muffler, and stock 2.25" SV... 13.00's on slicks all day long...
 
1 - 18 of 18 Posts
Top