4 bolt vs 2 bolt main

98stangv8 · Nov 26, 2008

How can you tell which you have? I have a custom build engine...is there something to look for on the engine itself that will tell you?

thanks!

Gearbanger 101 · Nov 26, 2008

Unless its an aluminum block or a Cobra iron block, it should be 2V of I'm not mistaken?

bdcardinal · Nov 26, 2008

technically iron are 4 bolt main, and aluminum are 6 bolt main. the cross bolts are main bolts.

98stangv8 · Nov 26, 2008

ok...with that, maybe you can help some. I am in the process of getting a Vortech V2, SQ installed...I have a 302 stroker with forged internals, Kellogg Crank...and the owner asked me how many bolt main I had.....I want to run approx 10-12 lbs of boost...he said that may be too much with a "2 bolt main"

any thoughts?

Thanks!

CobraRed_96_GT · Nov 26, 2008

98stangv8 said:
ok...with that, maybe you can help some. I am in the process of getting a Vortech V2, SQ installed...I have a 302 stroker with forged internals, Kellogg Crank...and the owner asked me how many bolt main I had.....I want to run approx 10-12 lbs of boost...he said that may be too much with a "2 bolt main"

any thoughts?

Thanks!

He's talking about the main bolts you'd use studs for. Ours have two main bolts and 2 side bolts. You have 2 main bolts. But the side bolts are what go first not the mains if im not mistaken.

Gearbanger 101 · Nov 27, 2008

98stangv8 said:
ok...with that, maybe you can help some. I am in the process of getting a Vortech V2, SQ installed...I have a 302 stroker with forged internals, Kellogg Crank...and the owner asked me how many bolt main I had.....I want to run approx 10-12 lbs of boost...he said that may be too much with a "2 bolt main"

any thoughts?

Thanks!

My thoughts are that he has no idea what he's talking about. His still got 302 OHV on his brain, not Modular OHC. I've seen guys run into the 600hp range with the stock nodular iron crank and 2V GT block and others running well into the 600-900hp range with the forged crank and 2V GT block, so that should be the least of your worries. The rods and pistons will go long before the crank or block does. The 6-bold mains are nice if you're going to be running a lot of sustained RPM, but for most applications, they're overkill.

98COBRA281 · Nov 27, 2008

98stangv8 said:
ok...with that, maybe you can help some. I am in the process of getting a Vortech V2, SQ installed...I have a 302 stroker with forged internals, Kellogg Crank...and the owner asked me how many bolt main I had.....I want to run approx 10-12 lbs of boost...he said that may be too much with a "2 bolt main"

any thoughts?

Thanks!

10-12 lbs is fine on a stock bottom end, with a forged motor, you could prolly run up to about 700+hp

+1 on the guy thinking its a 302 pushrod motor.....

twogts4us · Nov 30, 2008

Wait, the shop owner who is installing this SC for you doesn't know about mod motors? No offense, but why on earth did you pick him to do your install?
The 4.6L mod motor (ALL of em) have cross bolted main caps.

mogs01gt · Nov 30, 2008

98stangv8 said:
ok...with that, maybe you can help some. I am in the process of getting a Vortech V2, SQ installed...I have a 302 stroker with forged internals, Kellogg Crank...and the owner asked me how many bolt main I had.....I want to run approx 10-12 lbs of boost...he said that may be too much with a "2 bolt main"

any thoughts?

Thanks!

find another engine builder, he thinks you have a 5.0 ohv engine. Stock SOHC 2v engines have 4 bolt main and the DOHC 4v blocks have 6 bolts.

bdcardinal · Nov 30, 2008

mogs01gt said:
find another engine builder, he thinks you have a 5.0 ohv engine. Stock SOHC 2v engines have 4 bolt main and the DOHC 4v blocks have 6 bolts.

corrected for accuracy.

mogs01gt · Dec 1, 2008

bdcardinal said:
corrected for accuracy.

my bad, I meant 4.

98stangv8 · Dec 1, 2008

Thanks guys...this was a schmuck that worked there...not the owner...the owner is legit...this guy I guess just didn't have a clue..

Ok...to further the question...since you guys aced this questions..

I know this has been asked over with a stock engine..but with the forged internals on my build...how many pounds of boost would you say are safe to run with the Vortech?

How many pounds can I go until I have to upgrade the rib pulley system?

Thanks!

CobraRed_96_GT · Dec 1, 2008

98stangv8 said:
Thanks guys...this was a schmuck that worked there...not the owner...the owner is legit...this guy I guess just didn't have a clue..

Ok...to further the question...since you guys aced this questions..

I know this has been asked over with a stock engine..but with the forged internals on my build...how many pounds of boost would you say are safe to run with the Vortech?

How many pounds can I go until I have to upgrade the rib pulley system?

Thanks!

I don't quite know the specs. Have they been posted? Cobra crank? ARP main studs? Stock side main bolts? ARP headstuds? What type of pistons? Dish?
It's not an issue of PSI. Cuz one guy making 12psi with ported heads/LT's/blower cams will surely make more power in most cases than the guy with 14-15psi stock heads and manifolds. PSI is a measure of resistance, not flow.
Compression is the deciding factor of how much power you'll be able to run on pump gas, or how much you'll need to pull timing. Generally a forged shortblock should have no problems supporting a 6 rib kit vortech. But theirs random factors like getting any detonation on mahle 4032 grade pistons where it doesnt take much power to break.

Gearbanger 101 · Dec 1, 2008

98stangv8 said:
Thanks guys...this was a schmuck that worked there...not the owner...the owner is legit...this guy I guess just didn't have a clue..

Ok...to further the question...since you guys aced this questions..

I know this has been asked over with a stock engine..but with the forged internals on my build...how many pounds of boost would you say are safe to run with the Vortech?

How many pounds can I go until I have to upgrade the rib pulley system?

Thanks!

The amount of "boost" you'll be able to run will depend on the quality of your fuel and your ability to keep your air charge temperatures cool.

With 91-octane in your tank and no after cooling you'll probably be limited to 10-12psi.

Add race gas, water methanol injection, and/or an A/A or A/W intercooler and you'll be able to push it a lot harder without pulling so much timing.

Remember....boost figures should be used as a rough reference only. Airflow is what you're after. Boost is a measure of restriction on the intake side. A car seeing a lot of boost on the gauge may not necessarily be seeing a lot of airflow. Port and polish your heads and open up your intake and exhaust system and your "boost" pressure will drop, but your power levels will go up.

As far as pulley conversion....don't quote me on this, but I'm under the impression that guys are swapping out to 8-rib pulleys at about a 3.20" blower pulley. There are ways around it though. Increasing the diameter of your crankshaft pulley will also spin your blower faster (increasing boost) while allowing you to stick with the 6-rib configuration.

Realistically though, most guys even with forged internals don't push things much past the 425-475hp range with the S-Trim.....especially with a street car. That seems to be the limit of their designed efficiency range and you've also started reaching the limit of your stock fuel system. I've seen one example push it as high as 650hp on a fairly wild engine combination, but at that point you're running the blower waaaay out of its efficiency range, and shortening its lifespan dramatically. Not to mention you’re going to require an extensive and expensive revamp of your fuel and ignition system.

98stangv8 · Dec 2, 2008

Thanks guys...here are the specs right now:

9.8:1 compression
9cc dished pistons
Manley rods/pistons, Kellogg Crank
VT stage 2 heads , p&p
PI intake
ARP studs
custom grind conservative cam...was ground for a possible blower later from MPH

I think I got it all in there...does that provide any new insight over what gearbanger stated?

At what point do you have to upgrade exhaust to 3" pipes? What power levels?

Thanks for the help!

mogs01gt · Dec 2, 2008

With a built bottom end, the amount of power you can make will be based on your fuel system.

darkside03gt · Dec 2, 2008

the max you will ever see out of a s-trim is 14 psi or so. some have used s-trims to make 550 rwhp but they are spining the blower to its max rpm (52,000). if you are shooting for anything over 500 rwhp I recomend you get a SI or T trim upgrade.

Ryan441 · Dec 2, 2008

you can run 12psi on the stock bottom end at 9:1 compresion

CobraRed_96_GT · Dec 2, 2008

mogs01gt said:
With a built bottom end, the amount of power you can make will be based on your fuel system.

+1. Fuel system and type of fuel. I'd recommend some race gas added to 91 13psi and over on 9.8:1. May need a SCT BIg Air from pegging out a LMAF 90mm around 450-475rwhp.
If it was me and I didn't want to buy all that stuff I'd stop at when the 90mm maxed. That way you could still use a S-trim, maybe a single focus pump for cheap and a cheap MAF. Otherwise I'd say buy a T-trim or Novi 2k and actually build some power. You'll need to be pulling timing and running more octane than most to hit high boost - although 9.8:1 isn't too hard to work with.

98stangv8 · Dec 2, 2008

CobraRed_96_GT said:
+1. Fuel system and type of fuel. I'd recommend some race gas added to 91 13psi and over on 9.8:1. May need a SCT BIg Air from pegging out a LMAF 90mm around 450-475rwhp.
If it was me and I didn't want to buy all that stuff I'd stop at when the 90mm maxed. That way you could still use a S-trim, maybe a single focus pump for cheap and a cheap MAF. Otherwise I'd say buy a T-trim or Novi 2k and actually build some power. You'll need to be pulling timing and running more octane than most to hit high boost - although 9.8:1 isn't too hard to work with.

cool...thanks for the great info...I am just looking to keep this on and use it for a long time...didn't want to put too much into the motor and ruin it..

Could I go with a single focus pump now, or would I need to run a dual setup?

Will a single pump push enough for 400+rwhp?

Thanks!

How about exhaust...when you do need to go up to 3" pipes?

4 bolt vs 2 bolt main

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