03 cobra boost question?

nitrous408 · Jul 31, 2006

ok i got a 2.76 pulley. i just got my boost over lay goes to 16 psi .with the 2.76 pulley i got i have 13.5 psi boost.. some books say its suppose to be about 15 to 17 psi ..i was wondering of the lower pulleys you can get ,if i get the 4 lb lower .will it be 4 psi for real ""a true 4 lbs""? or should i get the 6 lb lower to be sure?..iam shooting for 16 or 17 psi. will i need to retune my car after this lower pulley swap? i was told but someone that the more air it sucked in the more fuel the computer would give it.. is this true or not thanks .

Uncle Meat · Aug 1, 2006

nitrous408 said:
ok i got a 2.76 pulley. i just got my boost over lay goes to 16 psi .with the 2.76 pulley i got i have 13.5 psi boost.. some books say its suppose to be about 15 to 17 psi ..i was wondering of the lower pulleys you can get ,if i get the 4 lb lower .will it be 4 psi for real ""a true 4 lbs""? or should i get the 6 lb lower to be sure?..iam shooting for 16 or 17 psi. will i need to retune my car after this lower pulley swap? i was told but someone that the more air it sucked in the more fuel the computer would give it.. is this true or not thanks .

Adding a 4lb will give you approximately 4 more psi, same with a 6lb lower, as long as conditions are optimal. YES, you will need not only a re-tune, but a butt load of supporting mods to handle the additional strain on the cooling & fuel systems if you decide to go this route.

First off, adding a 2.76 upper will only bring the boost up to 15.2 at the very best. This is taking into consideration the atmospheric conditions are just right and you're not experiencing any belt slip. What is the ambient temperature outside? The higher the temperature, the lower amount of boost you're going to make. This may account for why you're only seeing 13+ PSI. Additionally, you will only see this amount of boost at the initial hit of the throttle. The Eaton M112 is not a very efficient blower and is not capable of holding high boost very well in stock form, it just wasn't designed for it. As the RPM's climb and you over-spin the blower your boost will actually drop some.

Now if you add a 4 lb or a 6 lb lower you're going to be spinning that Eaton WAY past it's efficiency level in stock form. You're going to have nothing more than a giant heat pump when you're done! You'll be over spinning the alternator too so you'll need to deal with that while you're at it. I highly suggest you look at having the blower ported before adding a lower. Even with a ported blower 16 PSI is about the max you can make and sustain with all things being optimal. That setup (Ported Eaton/2.76 upper/4lb lower) though will require a bunch of supporting mods. Bigger heat exchanger, new or re-calibrated MAF (Mafia, MAF-Extender), bigger injectors, BAP, new pumps, etc.

I would get the blower ported for now and hope your 2.76 coupled with the new port job can still be safely run with the stock fuel system. To safely make, hold, & run 16+ lbs of boost from the Eaton will take more than just throwing a lower on your current setup.

U.M.

nitrous408 · Aug 1, 2006

Uncle Meat said:
Adding a 4lb will give you approximately 4 more psi, same with a 6lb lower, as long as conditions are optimal. YES, you will need not only a re-tune, but a butt load of supporting mods to handle the additional strain on the cooling & fuel systems if you decide to go this route.

First off, adding a 2.76 upper will only bring the boost up to 15.2 at the very best. This is taking into consideration the atmospheric conditions are just right and you're not experiencing any belt slip. What is the ambient temperature outside? The higher the temperature, the lower amount of boost you're going to make. This may account for why you're only seeing 13+ PSI. Additionally, you will only see this amount of boost at the initial hit of the throttle. The Eaton M112 is not a very efficient blower and is not capable of holding high boost very well in stock form, it just wasn't designed for it. As the RPM's climb and you over-spin the blower your boost will actually drop some.

Now if you add a 4 lb or a 6 lb lower you're going to be spinning that Eaton WAY past it's efficiency level in stock form. You're going to have nothing more than a giant heat pump when you're done! You'll be over spinning the alternator too so you'll need to deal with that while you're at it. I highly suggest you look at having the blower ported before adding a lower. Even with a ported blower 16 PSI is about the max you can make and sustain with all things being optimal. That setup (Ported Eaton/2.76 upper/4lb lower) though will require a bunch of supporting mods. Bigger heat exchanger, new or re-calibrated MAF (Mafia, MAF-Extender), bigger injectors, BAP, new pumps, etc.

I would get the blower ported for now and hope your 2.76 coupled with the new port job can still be safely run with the stock fuel system. To safely make, hold, & run 16+ lbs of boost from the Eaton will take more than just throwing a lower on your current setup.

U.M.

thanks btw i got the 2400 sct air mass, the boost did hit 14psi once..i got the idler pulley so belt wrap is good ,,but i do have some slip ,i noticed the black dust around the pulleys i got a 74.5 gaterback belt on it ,,,i was told the alum pulley ..which i got tend to slip more the stell pulleys ..is this correct? i could go with a gates 74.0 belt to make it tighter .you think that would help? i really didnt want the lower , but i want to max my 16 psi gauge out you know i to need a bigger h/e gords dont return my calls , i called 3 times and left message? yes i still got 39 lbs injectors..what you thank about what i just said ? thanks U>M> you been i real big help to me thanks.

TheDukeOfEarl · Aug 1, 2006

If you are looking for a heat exchanger there is only one. Get the AFCO double pass. Their products are pro grade. I run their adjustable shocks in the rear and their coil over springs front and rear. 400 lb fronts and 600 lb rears. This summers heat has been really rough. I havent been able to run full power for a 40 min race this summer. I only run a Billet flow 2.76 upper. If you go to 16 lbs boost you will have a lot of money to spend. You will need to up your flow rate. The stock radiator pump is not enough. Inline electric is the way to go. 55 GPM flow. Flow is everything!

A lot of people are confused about the two cooling systems. The engine cooling system needs to be balenced at 190. It needs to have high flow to remove hot spots but does not need a huge radiator. A big radiator will over cool the fluid and never reach a balence. The Heat exchanger is a different story. You want to remove as much heat as you can. There is no need to maintain 190 degs like the engine. It needs to get the charge as cold as you can. Big radiator. Good flow. Lots of cooling.

http://www.afcoracing.com/afco_hp.html

http://www.stewartcomponents.com/

Uncle Meat · Aug 1, 2006

nitrous408 said:
thanks btw i got the 2400 sct air mass, the boost did hit 14psi once..i got the idler pulley so belt wrap is good ,,but i do have some slip ,i noticed the black dust around the pulleys i got a 74.5 gaterback belt on it ,,,i was told the alum pulley ..which i got tend to slip more the stell pulleys ..is this correct? i could go with a gates 74.0 belt to make it tighter .you think that would help? i really didnt want the lower , but i want to max my 16 psi gauge out you know i to need a bigger h/e gords dont return my calls , i called 3 times and left message? yes i still got 39 lbs injectors..what you thank about what i just said ? thanks U>M> you been i real big help to me thanks.

I'm unfamiliar with any claims that steel pulleys grip better than aluminum. I do know that the non-slip pulleys do grip better than the standard pulleys though.
To safely run 16 PSI you will need some fuel system upgrades. The worse thing you can do is starve the motor for fuel because that will cause a lean condition and we all know that going lean on these motors is a bad thing. How much of a fuel system upgrade you'll need is debatable. You may be able to get away with just a set of larger injectors and a BAP. A call like that would have to be made by your tuner based on dyno tuning and wide band sampling.
As far as HE's go there are plenty out there to choose from, the Duke does a lot extended hard running with his snake so he's got first hand knowledge on heat soak and which HE's work best. If he says the Afco unit is good I'd tend to agree with him.

U.M.

SVT98Snake · Aug 1, 2006

LFP makes a good exchanger too.

Also...if you go ported, make sure you get a lower....you will lose boost if not. With just a upper, ported steg, and JLT I made 25 more rwhp. 50+ with a lower.

nitrous408 · Aug 1, 2006

SVT98Snake said:
LFP makes a good exchanger too.

Also...if you go ported, make sure you get a lower....you will lose boost if not. With just a upper, ported steg, and JLT I made 25 more rwhp. 50+ with a lower.

i like the gords unit ,but they dont return my calls? i was going to get the one with the fans. i just dont want to get a whipple or k/b right now or ever. k/b sales rep. really pissed my off. i didnt want to change fuel pumps or inj. but if i got to change inj no big deal. boost a pump not a problem either. i want to make as much power as i can with the eaton. getting ported next week. so what size lower you recomend? and what hp #s will i be expecting? thanks all. im new to this blower fuel inj. thing.

Uncle Meat · Aug 2, 2006

nitrous408 said:
i like the gords unit ,but they dont return my calls? i was going to get the one with the fans. i just dont want to get a whipple or k/b right now or ever. k/b sales rep. really pissed my off. i didnt want to change fuel pumps or inj. but if i got to change inj no big deal. boost a pump not a problem either. i want to make as much power as i can with the eaton. getting ported next week. so what size lower you recomend? and what hp #s will i be expecting? thanks all. im new to this blower fuel inj. thing.

If you couple a 4lb lower with your existing 2.76 upper, have the Eaton ported, and then ensure your car is getting all the fuel it needs I would expect you to be seeing 500 RWHP.

U.M.

DeVus1 · Aug 2, 2006

Lots of good information in this thread. As far as heat exchangers go, I really like the LFP design.

nitrous408 · Aug 2, 2006

or do you think i need to get a 74 inch gates belt first,i got a 74.5 inch gaterback grooved belt. that way i can see if i got more boost? maybe its belt slip? i know its slipping some every time i drive it ..belt dust..

Uncle Meat · Aug 2, 2006

nitrous408 said:
or do you think i need to get a 74 inch gates belt first,i got a 74.5 inch gaterback grooved belt. that way i can see if i got more boost? maybe its belt slip? i know its slipping some every time i drive it ..belt dust..

What is the temperature where you're currently at? I'd be willing to bet the lower boost you're experiencing is due to the temps, humidity, and elevation of your current location. I see 2lbs less boost in the summer compared to the winter myself.

U.M.

nitrous408 · Aug 3, 2006

Uncle Meat said:
What is the temperature where you're currently at? I'd be willing to bet the lower boost you're experiencing is due to the temps, humidity, and elevation of your current location. I see 2lbs less boost in the summer compared to the winter myself.

U.M.

im in baton rouge la. 90 plus deg...sea level ..if i get a whipple,,what else would i need....im thinking going whipple may be ..what size pulley to get on top ..and how much boost ,,and do i have to upgrade injector and pumps ..at a certian point a guess..? what hp would i have then with the whipple,more then the ported eaton i belive right ?

Uncle Meat · Aug 3, 2006

nitrous408 said:
im in baton rouge la. 90 plus deg...sea level ..if i get a whipple,,what else would i need....im thinking going whipple may be ..what size pulley to get on top ..and how much boost ,,and do i have to upgrade injector and pumps ..at a certian point a guess..? what hp would i have then with the whipple,more then the ported eaton i belive right ?

The heat is MOST DEFINITELY affecting the amount of boost you are currently seeing, GUARANTEED!

As for your other questions.... whipple will require bigger injectors and some fuel system work if you want to go north of 500RWHP. As for the pulley size up top? You'll have to ask the Whipple dealer you're purchasing from. They know what pulley combos equal a specific PSI. The whipple is capable of more than 600RWHP depending on your supporting intake/exhaust/fuel system mods.

U.M.

nitrous408 · Aug 4, 2006

is a whipple a twin screw or auto rotor type blower? going to call jms today.

Uncle Meat · Aug 4, 2006

Whipple and Kenne Bell are both classified as "Twin Screw" style superchargers.

If you want to learn where the terms "Autorotor" or "Lysholm" are derived from you can read a little about that here:

http://www.whipplesuperchargers.com/content.asp?PageID=80

U.M.

nitrous408 · Aug 5, 2006

Uncle Meat said:
Whipple and Kenne Bell are both classified as "Twin Screw" style superchargers.

If you want to learn where the terms "Autorotor" or "Lysholm" are derived from you can read a little about that here:

http://www.whipplesuperchargers.com/content.asp?PageID=80

U.M.

thanks U.M dose the whipple come with a boost bypass valve? or not ..? yes i got the credit with rpm outlet so i was going to get the kit from them , since they have it in stock , just neeed to know what the kit comes with? ..i called JMS they said for me to get 60 lbs inj, and B.A.P.,he said to send my 3 stage chip back in he would reburn it for free i got a dyno date in late sept. he said if i have 16 honest psi boost i should see 600 rwhp. i allready got the big air sct.#2400, so does it have a bypess valve in the kit ..rpm outlet is fishy...i think the 3 in pulley is what i need...i been adding every thing up for lower pulleys. port eaton,bigger h/e etc.for only 500 rwhp .so i fuigued i bump ot for the whipple ..kenne bell takes to long to get a kit made 2/ 3 weeks .the whipple i can get in 2 days.with my choice of pulley ...humm they got a 2.75 pulley too.? give me some feedback .,.thanks the rods and pistons are manleys right ? i shouldnt have any problem if tunes right.?

03 cobra boost question?

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