Is 2.76 upper safe for year round daily driver ?

2004 Cobra with mods listed in sig. I'm considering whether to run a 2.76 or 2.93. I have the 4-idlers from BF, and custom tunes from Amazon. Daily driver 5-6 days a week year round, including some in-state highway trips. No street racing. Drag strip maybe a couple times a year. My goal is to eventually get into the 11's at the strip on DR's but with a 100% streetable daily driver.

I DON'T plan to port the Eaton or go with bigger injectors, BAP, etc.
No plan to run a bigger lower pulley.
I have NO cooling mods currently.

Call me a wimp, but I'm waiting for my warranty to run out before the pulley goes on (another 17 months !):bash:

And yes I did search through over a hundred polls looking for this answer.

If you ran one size and decided to switch, I'd appreciate your comments. Thanks.

I drive mine daily as well w/ a 2.76 upper in Florida heat as well. Biggest concern is the pulley ratio, and RPM of the Eaton. There are plenty of guys around running 2.76 & 4lb, 3.1 & 6lb and doing fine. Mine is yet to run hot, and I use to do quite a bit of racing a night..never ran hot. I'm sure you'll be fine, nothing to worry about.

I'm running a 2.80 upper, no lower, with a heatexchanger. Daily driven, in Florida, 40 miles a day if all I do is to and from work, 5 to 6 days a week. No problems to speak of except a shredded belt that was on its way out already when I installed the pulley.

hell yeah- add a 2lb lower and a stage 4 stiegemeier while you are at it:coolman:

Do the 2.76 and never look back! I have almost 40k miles driven with a 2.76 upper and zero issues.

I voted "Use 2.76 + tune, no cooling mods are required"

Cooling mods are not required but they can only help.

I have always told anyone asking me about cooling mods:
"More cooling is always a good thing!"

Mine was my daily driver up until last week, no problems whatsoever. Mods and numbers are in my sig. You won't regret it. Before the 2.76 I had the 2.93 on there and it made 444RWHP and 466TQ. The 2.76 really woke her up! DO IT!!!:rockon:

Bump for the POLL
Thanks guys for your input, let's hear from EVERYONE !

I've got the 2.93 on my DD and though I did consider the 2.76 for some time, in the end I chickened out. The 2.76 over spins the blower quite a bit and I was concerned about the heat. I'm sure that most will say the 2.76 is fine. I just wanted to be cautious. Either pulley is a probably a good choice.:beer:

The stock HE will work fine if you just DD the car and don't get into boost all the time.....

A HE upgrade will only help keep the Eaton from geeting heat soak as easy when you are beating on her.

In other words, with a LFP HE as I have, you can go hard a lot and not loose power (as much) cuz of heat soak and run more consistantly.

Even with the HE upgrade with a 2.76 its gonna build heat.....the new HE will just do a better job of controlling it.

But if you just DD the car it will not be building boost therefore the heat will be ok for DD


Go 2.76 if you are not going with a lower. A 2.76 is almost the same as a 2.93/4# lower combo.....

I suggest getting it dyno tuned if you can find a tuner. They can get you a tune "specifically" for your car.

I tried to do as much research on this same question as I possibly could, and I came across an article in the Nov 2004 MM&FF (three part, Mods for 4V Mods)

They ran lot’s of test on an engine Dyno; not a Chassis Dyno, the results were very interesting.

The 3.2 pulley made 30 more peak hp & 40 ft\lbs of torque & +2lbs of boost, after 5500 rpm it lost about 1lbs of boost to 6500.

The 2.93 made only 8 more hp than the 3.2 but torque jumped 45 ft\lbs and +2 more lbs of boost (13.3lbs peak boost)

The last test was the 2.93 upper and a 7.75 lower (7.5 lower is stock) this is basically like running a 2.8 upper and stock lower.
Peak hp was up only 1hp, but torque went up about another 20 ft\lbs, boost now had a peak of 14.5 ft\lbs

The caveat to all this is that the engine was run with open exhaust (manifolds or headers with an extension tube only no cats, mid pipe or mufflers), No MAF or air filter (the dyno was equipped with a F.A.S.T engine management system), no accessories (alternator, power steering pump or water pump). And most important no additional idlers or sure grip style of upper pulley (I’m sure some major belt slippage was going on)

I also talked to half a dozen guys running Eaton blowers, I decided that you can only harness so much torque with the IRS and street tires, yea it would be nice to say I have xxx ft\lbs of torque, but my wife and I both have a hard time keeping the tires planted with just minor mods on dry pavement much less wet.

That’s why I decided on a RR 2.9 (brandy says it’s purdy, just kidding) if it’s a DD and you have to drive the car in all kinds of conditions, think what it’s gonna be like trying to merge onto highway traffic in the rain with 450+ ft\lbs of torque, and we all know the traction control sucks!

And if your going to eventually get serious, save the $1000 bucks you would spend on another tune, a better Heat Exchanger, pully, belt, anti-freeze, wideband gauge, boost gauge, labor and dyno time and put it towards a KB and another tune, a better Heat Exchanger, anti-freeze, wideband gauge, boost gauge, labor and dyno time.

Just my opinion, good luck with the car, and ain’t rag tops cool?

Lee

its cool just make sure you get a good dyno tune....

stallwle said:

think what it’s gonna be like trying to merge onto highway traffic in the rain with 450+ ft\lbs of torque

Lee

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Good point, it does get wet down here in the "Sunshine State"...and this car doesn't stay at home just cause it rains.
If it snows, I may take the bus...LOL

Cobra-21

micah2003svt said:

its cool just make sure you get a good dyno tune....

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I get mail-order tunes from Rick & Linn at Amazon Tuning Services. They have a great reputation here as giving excellent tunes, having done hundreds at their shop and by mail order. In fact there are several others on the forums that are in very good standing, but I chose ATS. If I was closer to N.C. I'd be on their dyno for sure. After I finally install my pulley and new tune, I'll be off to the local dyno to check the A/F ratio and my new numbers. But the local guys don't seem to have a clue about Predators so I'll leave the tuning to Rick...

Cobra-21

I run a 2.76 on my 2.2L KB and it was daily driver for quite a while.
I had a 2.76 on my un-ported eaton and then on my ported eaton as well.

unit213 said:

I run a 2.76 on my 2.2L KB and it was daily driver for quite a while.

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I'm thinking the KB and Whipple are in a different universe as far as efficiency and heat generation, so they can handle more boost before adding heat. But the ported eaton? Is that just a power adder or does it improve efficiency and reduce heating also? Reason I ask is, a lot of advice on the forums says if you run a ported Eaton you should also "add the cooling mods".
Cobra-21

I vote for the 2.76. I also drive my car daily, and to this point do not have any colling mods (just waiting for next years mod budget). The car runs great, and I have driven both a 2.93 and a 2.76. It does feel different! But I would recommend not going with a mail order tune. I figure if you are going to do it, do it right. You think you will save money by not driving to whatever tuner you choose (rick at amazon, or dan at pro-dyno) and just ordering a mail order. But every car is different. If all the cars were the same, we all would be making the exact same hp/tq numbers with similar mods. You HAVE to get it on a dyno, and tune YOUR car!!!! Just my 2 cents!

I'm currently running a 2.76" on my Stage IV ported Eaton. I'm also running a LFP heat exchanger and coolant tank. I think they're necessary with the constant heat and humidity here in Florida.

I have more than 1000 open track miles this year. All on my BF 2.76 and stock lower... I've never limped the car..

Cobra-21 said:

I'm thinking the KB and Whipple are in a different universe as far as efficiency and heat generation, so they can handle more boost before adding heat. But the ported eaton? Is that just a power adder or does it improve efficiency and reduce heating also? Reason I ask is, a lot of advice on the forums says if you run a ported Eaton you should also "add the cooling mods".
Cobra-21

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I have zero cooling mods. A HE isn't a cooling mod so I don't include that,
even though I have one. My point was that I'm making 100rwhp more
than an Eaton car with the 2.76 upper and everything is fine.