Whats next? 10% lower or headers or both?

[sask10]

I just finished having my car tuned by Jon Lund and the car feels strong but I'm looking for a bit more. I have a VMP TVS Gen I(2.5" upper), CJ dual 65mm TB, JLT 123mm intake, ID725s and an offroad xpipe. I want to stay running pump fuel (94 octane) and I do use torco for safety. Could this setup handle a 10% lower and be safe with pump fuel with no mods other then the ID725s to the fuel system? How about headers, worth adding to mix?

 

[nxhappy]

10% should be OK but you should log the duty cycle afterwards. You might want a booster for the pumps.

 

[Phantomhalo]

+1 on the logging duty cycle and the 10% lower with booster. You should be good to get headers too. With the headers and 10% you will get a nice bump in power. Injectors may need to be upgraded but I've seen guys running 72's with those mods. Talk with your tuner to be safe.

 

[96chargedcobra]

I'm running a 2.4 upper, 15% lower with tge 725s and a boost a pump and have plenty of room.

 

[Mainn]

725's are fine unless you run E85.

If you run with Torco all of the time, the 10% lower is fine. You'll have 19-20psi of boost with that setup and the 2.5" upper (18-19psi with headers). If you want to stay on pump fuel, I wouldn't do the lower.

Either way, I would do headers before the 10% and turning up the boost.

 

[sask10]

This maybe a stupid question but how are those peak boost #s arrived at? Is it directly related to engine RPM, for example said supercharger on said engine with associated mods will produce Xpsi at peak engine RPM? If so what RPM are those numbers at? I wouldn't opposed to limiting engine rpm to say 6K to stay away from those "peak #s" if the trade off was more/flatter hp/torque curve lower in the RPM range.

 

[Van@RevanRacing]

This maybe a stupid question but how are those peak boost #s arrived at? Is it directly related to engine RPM, for example said supercharger on said engine with associated mods will produce Xpsi at peak engine RPM? If so what RPM are those numbers at? I wouldn't opposed to limiting engine rpm to say 6K to stay away from those "peak #s" if the trade off was more/flatter hp/torque curve lower in the RPM range.

Peak Torque with your set up is usually found between 3,750 to 4,500 RPM and peak horsepower is normally seen toward the upper RPM Range.

With your set up adding a 10% OD will add 3-4 PSI of boost. With your current set up you're likely in the 16-17 PSI range depending on Density Altitude. What did your dyno sheet say peak Boost was?

As a Lund Racing Dealer I work with customers like yourself on a daily basis. If you were to add a 10% OD and continue to run pump gas Lund would advise you to Add a Dual BAP as the Fuel Pump Duty Cycle is going to max out. Additionally you might have to go to a slightly larger upper pulley on the supercharger to prevent having too much boost. Max boost on pump gas is 18 PSI. With the cooler air arriving in can increase so it's always better to play it safe and lower your boost.

Long Tube Headers with an off road pipe tend to shed 1 to 1.5 PSI on average. So that should be taken into consideration when doing your analysis. 2.5 Upper Pulley at 17 PSI with a 10% OD adding 3 PSI takes you to 20 PSI. (TOO MUCH FOR PUMP GAS) Adding long tube headers could potentially reduce that to 18.5 to 19 PSI which could be the max.

Van

 

[ZOMBEAST]

I was running the VMP Gen 1 with 2.5, 10% lower, 1-7/8 longtubes, O/R X, 3 inch exhaust, 123 CJ intake, and L&M 72 TB. This netted me just a tad over 20 psi. I like to drive around with my 100 octane tune with 19 degrees of timing. I have driven it hard on the street with 93 and Torco, but I wouldn't feel comfortable running that at the track. I have a 16 degree tune which would be ok, but the exhaust sounds like shit.

I also run a dual fan exchanger, and radiator I got from Van, and a Reische T-stat. These are good items to lessen chance of detonation.

You could also check into meth injections too.

If you add the longtubes with your O/R, You'll open up another can of worms trying to get the sound right.

 

[Speedboosted]

Headers first, it will do more for the car now and in the future than the lower would IMO. Plenty of people run over 18 pounds on pump gas. Should you? Probably not, but the fact that enough people are means it's not going to instantly blow. I would do both personally and just have a tune with a bit lower timing for the colder weather.

 

[brian98svtsnake]

Headers for sure, will lower boost and increase engine efficiency. Or both at the same time which will probably keep you at the same boost level.