Need help with supercharging a 6.2

[Orange Bomber]

Hey everybody, long time reader first time posting so bare with me if this rough. Lets start off with what I have, 85 6.2 block ARP head studs, full length main girdle, gear drive, dual 3" exhaust and a vortech v2 s-trim supercharger. I know everyone says that 10 psi is about max give or take a little but with those mods how much higher can you push it? So depending on that I'm trying to decide on what pulley to use for the supercharger drive pulley. Right now my lower is an 8" and the upper is a 3.47, with that I'm pushing about 1 psi at 2000 rpm and 3psi at 3000. The pulley I'm looking at getting is 2.50" and would when i asked vortech about it they said it would get me about 10-11psi at 2000, and about 15 at 3000rpm. How well can a 6.2 hold up with that kind of sustained boost levels? Sorry if i rambled a little, any advice would be great thanks.

 

[folkenheath]

Pump gas? Intercooled? What's your compression?

With a centrifugal supercharger they are much more efficient at higher RPM yet you are stating low rpm numbers, what is your boost at the upper RPMs?

Here is a chart from Procharger that shows some guidelines for centrifugal supercharging on pump gas...

Your engine may give up the ghost before these limits apply too...

 

[imiceman44]

Hey everybody, long time reader first time posting so bare with me if this rough. Lets start off with what I have, 85 6.2 block ARP head studs, full length main girdle, gear drive, dual 3" exhaust and a vortech v2 s-trim supercharger. I know everyone says that 10 psi is about max give or take a little but with those mods how much higher can you push it? So depending on that I'm trying to decide on what pulley to use for the supercharger drive pulley. Right now my lower is an 8" and the upper is a 3.47, with that I'm pushing about 1 psi at 2000 rpm and 3psi at 3000. The pulley I'm looking at getting is 2.50" and would when i asked vortech about it they said it would get me about 10-11psi at 2000, and about 15 at 3000rpm. How well can a 6.2 hold up with that kind of sustained boost levels? Sorry if i rambled a little, any advice would be great thanks.

well I know you reinforced your bottom end and maybe your heads, but if you still have the stock pistons, I wouldn't suggest you go higher thn 8 sustained and 10-11 max for short periods.
If you get some lower compression pistons, you could go up to the numbers you have with the new pulley.
You might be able to get away with it if you intercool, but you want to have a Pyrometer and watch your EGT's very closely, I believe 1100 degrees is what you wanna keep it below or you'll melt your pistons.

 

[imiceman44]

Diesel
You are in the diesel forum after all.

Pump gas? Intercooled? What's your compression?

With a centrifugal supercharger they are much more efficient at higher RPM yet you are stating low rpm numbers, what is your boost at the upper RPMs?

Here is a chart from Procharger that shows some guidelines for centrifugal supercharging on pump gas...

Your engine may give up the ghost before these limits apply too...

 

[Orange Bomber]

Pump diesel, no intercooler, stock compression. Right now I'm getting 3psi at 3000 I didn't see to much after that. I know these type of superchargers work better with the higher rpms and thats why I'm looking into the 2.5 pulley because that would make my SC spin at 23000 rpm vs 16000rpm it is now. I'm just worried about over boosting my motor.

 

[imiceman44]

Pump diesel, no intercooler, stock compression. Right now I'm getting 3psi at 3000 I didn't see to much after that. I know these type of superchargers work better with the higher rpms and thats why I'm looking into the 2.5 pulley because that would make my SC spin at 23000 rpm vs 16000rpm it is now. I'm just worried about over boosting my motor.

You don't want to overboost this engine as it is, if you can find a puley in between these two you'll be golden, and once you have the boost, I don't think you'll want to rev it beyond 2500 unless you are trying to race it, but for just driving around or towing, I think you'll be fine with something in between.

 

[Orange Bomber]

I hadn't planned on putting an intercooler in, I was looking at water/meth but wasn't to sure on that. Is 8 sustained and the 10 max because of high egts or because risk of blowing head gaskets or other parts? If i can keep egts down does that mean higher boosts or am I always limited by compression and head gaskets blowing out? There are i think six pulleys in between what I have and the 2.5, so 1-2 psi with each pulley is what the company says.

 

[folkenheath]

Diesel
You are in the diesel forum after all.

Ha ha, you got me. I saw vortech supercharger and didn't even think diesel and never checked the forum (I saw it from the new posts link).

2nd dumb post of the day, I'm on a roll! That reminds me of the real reason why I am moving, I read that 90% of all accidents happen within a few miles from home, so we are moving.

 

[imiceman44]

I hadn't planned on putting an intercooler in, I was looking at water/meth but wasn't to sure on that. Is 8 sustained and the 10 max because of high egts or because risk of blowing head gaskets or other parts? If i can keep egts down does that mean higher boosts or am I always limited by compression and head gaskets blowing out? There are i think six pulleys in between what I have and the 2.5, so 1-2 psi with each pulley is what the company says.

It's the EGT's that are the biggest concerns since you already put a girdle on the bottom end and ARP studds for the heads.
If you can monitor the EGT's and possibly do water injection to keep them cooler you could get away with the 2.5" pulley, but I still don't know the intended use of this engine?

I still wouldn't go too much higher try to keep your max at under 15, but if it were me 8-10 is plenty

 

[imiceman44]

Ha ha, you got me. I saw vortech supercharger and didn't even think diesel and never checked the forum (I saw it from the new posts link).

2nd dumb post of the day, I'm on a roll! That reminds me of the real reason why I am moving, I read that 90% of all accidents happen within a few miles from home, so we are moving.

 

[Orange Bomber]

The truck is my daily driver and something to hit the trails(mostly trails and rocks) with when i can, I rarely tow and nothing ever seriously heavy. I know my truck will never run liked a striped cat but making my truck a faster would be quite nice.

 

[imiceman44]

The truck is my daily driver and something to hit the trails(mostly trails and rocks) with when i can, I rarely tow and nothing ever seriously heavy. I know my truck will never run liked a striped cat but making my truck a faster would be quite nice.

In that case just go with the next size down or 2 you'll still be around 10psi and maybe 11-12 max and if you keep your eye on it you'll be fine and you will like the feeling.

 

[KirsL]

On a fully stock 6.2/6.5 12lbs of boost is the max you want to see. When pushed past that you will either blow the headgasket (if lucky) or break a piston/rings and really have a disaster. Now having headstuds and a strenghtened bottom-end but still stock compression I would still keep it limited to 12lbs if non-intercooled. If you run an intercooler with stock sompression you can push it to 15-18lbs. Now if you where to have run low comp pistons you could push it upwards of 25lbs. I now of some guys runnng over 40lbs of boost , but they're willing to have the engine blowup in the name of max power.

The real question is though is what have you doe in terms of fueling mods? Stock injection pump just turned up? Or are you running a bigger/modified pump?

Pushing extra air into these engines is actually pretty easy. The hard part is controlling the heat that power will make and having enough fuel to create it in the first place. Since you're running true dual exhaust I'd recommend you run 2 egt gauges to monitor both banks of cylinders. Temps you can run 950 maybe 1000 egts for long periods of time. For short bust like an on ramp say you can push it a little over 1200, but only for a few seconds. Otherwise bad things will happen.

Oh speaking of heat, have you checked/upgraded you cooling system yet? Coolant temps are something you have to watch when making more power with these engines. Actually even stock they REQUIRE a good cooling system.

 

[Orange Bomber]

For fuel I'm running a newly rebuilt 4544 pump turned up a 1/4 turn right now. As for cooling, nothing special just my stock radiator from the 68 gas motor and dual electric fans from a windstar. But my water temp always stays in the 180 range. And are dual pyro's extremely necessary or will one be fine?

 

[KirsL]

You should be good on fueling to make us of the amount of boost you'll be pushing. Obviously you can adjust the boost or fueling depending on how much smoke the truck is making. A lite haze to no smoke is best, means you're getting a good clean burn of the fuel.

Smoke is just wasted fuel, so the more smoke you make the more money you waste.

A 68 rad huh? Is this in a first gen truck? If the radiator is sized for a big block, it shouldn't have any issues cooling a 6.2. Just keep an eye on temps when its hot out and if you're pushing the engine hard. They can build heat very quickly.

While you could get by with one egt gauge, I'd prefer too but that's me. I like to monitor as much as I can. Do at least one for now. You can always put in a second one later on.

 

[Orange Bomber]

Awesome that answered my next question of how to tell if i need more fuel or less.

Yea its a '68 lb and it came with a 327 stock but the radiator in it is huge and its worked so far, I'll just keep my fingers crossed that'll still cool it enough.

Also today while I was showing my dad my truck he noticed a few places that I missed that were leaking air, so just waiting for the jb weld to dry and put it back together and see what kinda difference that'll make.

 

[Orange Bomber]

So everything is back together and no drastic changes the boost just comes on quicker, starts at 1400rpm instead of 2000 and now my max is 5psi. So I'm going to check around and see if anywhere local can get me a smaller pulley. I'm thinking a 2.95 will work best for now, that'll get me the 10ish max and if i really want to get more I'll have two sizes smaller to play with!

 

[imiceman44]

So everything is back together and no drastic changes the boost just comes on quicker, starts at 1400rpm instead of 2000 and now my max is 5psi. So I'm going to check around and see if anywhere local can get me a smaller pulley. I'm thinking a 2.95 will work best for now, that'll get me the 10ish max and if i really want to get more I'll have two sizes smaller to play with!

Well the good thing is you want it to be coming on earlier, and if you can get your 2000RPM boost in the 8-9 PSI youd be golden, that is the RPM you will be cruising at hopefully if your gearing is good.

 

[Orange Bomber]

I called 4wheelparts this morning and they can get me a new pulley but they cant order it till Monday. I hate figuring out what I need to buy right before the weekend! So if i move down three pulleys to the 2.95 it should be 7-8 psi at cruising or close because going 65 or so I'm just under 1800.

 

[imiceman44]

I called 4wheelparts this morning and they can get me a new pulley but they cant order it till Monday. I hate figuring out what I need to buy right before the weekend! So if i move down three pulleys to the 2.95 it should be 7-8 psi at cruising or close because going 65 or so I'm just under 1800.

Yeah your optimum for mileage is 1800-1900 so 65-70 you'd be in the 1800-2000 range which should be great, now if you could get the 8PSI there, youd be fine for occasionnal 3000RPM's