Another OHV M90 build

[Dono]

Headers, a borla muffler, and see about a high flow style(Like hollow) cat?

Probably next logical choice.

 

[Dono]

Whens enough enough?
I zeroed my max boost memory on my boost gauge, and id say max boost is 4psi.
I found this used, and cheap.
Worst case, I pull it off.

 

[jd4242]

Whens enough enough?
I zeroed my max boost memory on my boost gauge, and id say max boost is 4psi.
I found this used, and cheap.
Worst case, I pull it off.

You need to measure the exact size of both those pulleys.that pulley looks big to be 10% less than a 3" pulley.your need a new tune if you put a smaller pulley on.personally i would focus on the exhaust.4lbs off a 3" pulley sounds really low,people are getting way more than that off that pulley.

 

[Dono]

I'm looking at a gibson cat back with 2 1/2 piping to see if its worth while (Add shipping, and it probably isn't worth while). If this doesn't fly, I'll have something done locally.

James thinks I could go to about 7psi without inter-cooler. I have no idea to be honest.
And yes, some massaging of the tune would be required. I am interested to see what kind of added boost this would provide. Even without the exhaust, the $/horsepower gained points to the pulley.
Efficiency? Exhaust would be next for sure. Money talks though. At least I'll be able to post my experience with it.

 

[jd4242]

I'm looking at a gibson cat back with 2 1/2 piping to see if its worth while (Add shipping, and it probably isn't worth while). If this doesn't fly, I'll have something done locally.

James thinks I could go to about 7psi without inter-cooler. I have no idea to be honest.
And yes, some massaging of the tune would be required. I am interested to see what kind of added boost this would provide. Even without the exhaust, the $/horsepower gained points to the pulley.
Efficiency? Exhaust would be next for sure. Money talks though. At least I'll be able to post my experience with it.

Measure both pulleys with a caliper, that will be very good info.just no built motor or sc car uses "stock" exhaust for a reason,but i hear you on $$/hp

 

[Dono]

JD, your like the devil on my shoulder.

I called a friend of mine that runs a custom exhaust shop (I don't know why I didn't think of him before).
He says to stop by for a beer after work, and he will put my truck up on the hoist and have a look. He's talking one high flow cat, and a big a$$ exhaust. I spoke about the gibson cat back with 2 1/2 inch pipe, and he said not to. Very expensive, and it would not perform well.

He scared me. It is my daily driver, and I want it to flow well, and be quiet. I'd think that would be a challenge. He likes Magnaflow, so that should be a good thing, as long as he doesn't talk me in to going too big on the piping.

haha, more to come on this one. I'm afraid, very afraid.

Btw, I don't own a caliper.

 

[rocket 5979]

JD, your like the devil on my shoulder.

I called a friend of mine that runs a custom exhaust shop (I don't know why I didn't think of him before).
He says to stop by for a beer after work, and he will put my truck up on the hoist and have a look. He's talking one high flow cat, and a big a$$ exhaust. I spoke about the gibson cat back with 2 1/2 inch pipe, and he said not to. Very expensive, and it would not perform well.

He scared me. It is my daily driver, and I want it to flow well, and be quiet. I'd think that would be a challenge. He likes Magnaflow, so that should be a good thing, as long as he doesn't talk me in to going too big on the piping.

haha, more to come on this one. I'm afraid, very afraid.

For the power you are making a 2.5" single pipe will flow sufficiently so as not to restrict exhaust flow. Doing a single 3" would be total overkill, and if he wants you to go bigger than that then it would be a complete waste. Most people go way too big way too early for no good reason besides that they think it will flow better. It ends up being a waste of money and time.

I like Magnaflow too. Good mufflers and great somewhat aggressive sound without being too obnoxious.

 

[jd4242]

JD, your like the devil on my shoulder.

I called a friend of mine that runs a custom exhaust shop (I don't know why I didn't think of him before).
He says to stop by for a beer after work, and he will put my truck up on the hoist and have a look. He's talking one high flow cat, and a big a$$ exhaust. I spoke about the gibson cat back with 2 1/2 inch pipe, and he said not to. Very expensive, and it would not perform well.

He scared me. It is my daily driver, and I want it to flow well, and be quiet. I'd think that would be a challenge. He likes Magnaflow, so that should be a good thing, as long as he doesn't talk me in to going too big on the piping.

haha, more to come on this one. I'm afraid, very afraid.

haha more air in more needs to get out3" cats to a muffler reduced to 2.5 is perfect for the ohv.dont let him talk you into running any bigger than 3 and that depends on the muffler,if its a chambered muffler you "may" get away with all 3" but i would stick to 2.5 after the muffler.gibson is very over rated,sounds good tho.still would like to see the measurements of those pulleys.from what ive read they have 3 different stock pulleys,3'',3.3'' and 3.55''.if your only getting 4lbs off a 3" pulley im going to be real pissed if get less than 3lbs off my 3.25.guy before me said he was getting 4-6lbs off the 3.25

 

[Dono]

Thanks JD/Rocket, I'll make sure I don't end up with these monster pipes that do nothing but make my truck louder. 2 1/2 piping it is.

 

[Dono]

No question JD,
I'm sure the guys will have a caliper at the shop tonight. I'll measure sizes of pulleys.
Then when I change, we can see first hand boost differences in sizes.

 

[jd4242]

No question JD,
I'm sure the guys will have a caliper at the shop tonight. I'll measure sizes of pulleys.
Then when I change, we can see first hand boost differences in sizes.

yea i would love that info,got me worried now and if i dont see good boost off the 3.25 then i need to redo my math and send back the 2.7 before i use it and get me a smaller pulley to get near 9lbs
ps my truck will be done this weekend

 

[Dono]

my truck will be done this weekend

I can hardly wait! There's a good chance you will see more boost with your M90 completely rebuilt, and your rotor clearances tighter. In the end, who knows till you are running it.

I have to say, 4lbs boost gives me a whack of bottom end. The boost gauge doesn't show its going above 0 psi either. Really, I will be interested in the pulley change to get an idea on how psi relates to horsepower on our motors.

 

[rocket 5979]

I have to say, 4lbs boost gives me a whack of bottom end. The boost gauge doesn't show its going above 0 psi either. Really, I will be interested in the pulley change to get an idea on how psi relates to horsepower on our motors.

What boost gauge are you running? What is the maximum swing range of pressure and vacuum?

 

[Dono]

its a cheeper swing guage. Glowshift. Its sender is under the hood.

vac is around 20, and boost is 4-5psi max.

We caliper'd the pully's and here is what I have:

2.9" currently installed. looks factory.
2.7" is the 10% pulley.

Exhaust recomendation:
Cut all 4 (Yes, 4) cats out.
Slip 2 1/4" pipes over the pre-Y up at the motor and weld. Combine to a 4"collector, and thru a high flow cat (Good for a 460 motor), then reduce to 2 1/2" pipe and run thru a Magnaflow muffler.
I asked about headers, and he didn't think I would really notice a difference after I had opened up the flow. Glenn felt the stock exhaust was a bottleneck from factory (4 cats, and a low flow muffler) and that if we fix that, there will be a massive difference without headers.

He will give me a deal, but on the condition that I let him drive it before and after exhaust mod.

Also, he didn't suggest bothering with my new pulley until I open the exhaust.

Rocket, I think what is being said is that boost might not rise too much with the opened up exhaust and the new pulley as some of the back preasure is being relieved.

I do trust Glenn, as he does the exhaust on most of the city's hot rods.

 

[Dono]

Inquiring minds had to know....
I installed the pulley to see.

Boost comes on a bit quicker, but instead of topping out at 4-5lbs boost, it continues to climb to about 10lbs at rpm's rise.

I didn't notice any detonation, or ill effects. edit..detonation at part throttle. Original pully is back on.

Im sure James is starting to get pissed at me for making changes, so I will wait till exhaust is done, then add the pulley. Then send him logs to look at whenever he can fit in some time. I can always put the original pulley back on after logging.

I need to send him some cash just to keep him on retainer. He hasnt asked for a dime from me so far, even after offering. He will need to add up the time he's spent at some point soon. I sure would like to send him something soon. He's been very good to me.

 

[rocket 5979]

its a cheeper swing guage. Glowshift. Its sender is under the hood.

vac is around 20, and boost is 4-5psi max.

We caliper'd the pully's and here is what I have:

2.9" currently installed. looks factory.
2.7" is the 10% pulley.

Exhaust recomendation:
Cut all 4 (Yes, 4) cats out.
Slip 2 1/4" pipes over the pre-Y up at the motor and weld. Combine to a 4"collector, and thru a high flow cat (Good for a 460 motor), then reduce to 2 1/2" pipe and run thru a Magnaflow muffler.
I asked about headers, and he didn't think I would really notice a difference after I had opened up the flow. Glenn felt the stock exhaust was a bottleneck from factory (4 cats, and a low flow muffler) and that if we fix that, there will be a massive difference without headers.

He will give me a deal, but on the condition that I let him drive it before and after exhaust mod.

Also, he didn't suggest bothering with my new pulley until I open the exhaust.

Rocket, I think what is being said is that boost might not rise too much with the opened up exhaust and the new pulley as some of the back preasure is being relieved.

I do trust Glenn, as he does the exhaust on most of the city's hot rods.

When you open up flow or change a cam to something more aggressive then yes read boost will decrease as overall airflow increases. I wasn't really talking about that since I assumed you already knew that. I was more referring to where you mentioned that even though you were in boost the gauge itself wasn't reading anything.

 

[Dono]

Oh i get it Rocket. I guess I was trying to make sense of all the low end torque even though the guage shows vacuum. The M90 must still be helping, even though the guage isnt showing positive displacement.

 

[rocket 5979]

Oh i get it Rocket. I guess I was trying to make sense of all the low end torque even though the guage shows vacuum. The M90 must still be helping, even though the guage isnt showing positive displacement.

While WOT or just part throttle?

 

[Dono]

I get what you are saying. More power at part throttle body would still mean vacuum as the butterfly in the tb is still restricting air. This restriction shows as, vacuum on the Guage.

So, to put it simply, at part throttle, there is less vacuum than there was before, giving more power. That's it, isn't it?

Sorry, had to correct this stupid PlayBook corrections. Wording fixed

 

[Dono]

Btw, James says "no problem" on sending him new logs after I make changes to the exhaust and pully. Is he crazy? Maybe he's curious enough that he wants to see the difference the changes will make? My explorers running so good with the current tune, I'm questioning making any more changes.