Stock Shortblock, 350-375 Hp With Hci?

[94RioRedSnake]

This is my first post, so hopefully I'm posting in the right place with the right etiquette.

I have a 1994 cobra with a stock shortblock. I've been looking at a lot of forums and it seems it's possible to get 350+ hp out of a stock shortblock n/a using the right combination. I'm really impressed with the results using the 11R 190cc heads. What other supporting mods would I need to get the most out of those heads? Obviously a new cam and maybe my cobra intake ported by TMoss would flow enough?

I'm considering learning tuning and getting a quarterhorse for a tune, or else I would take it to a pro and get it tuned. What about exhaust, cai, MAF, tb? I think I would need a new fuel pump, but are the stock 24# injectors enough? Seems like I would need somewhere between 24# and 30#. I'm trying to get an idea of what the HCI and all of the supporting parts would cost me. Thanks.

 

[FastDriver]

Custom Cam: Go to Ed Curtis (then you can ignore everything else I say and just take his advice) No need for something radical, IMO. A good street friendly HR cam will do the trick

36 lbs or 42 lbs injectors
No to the Cobra Intake. You're looking for an RPM II or Systemax II intake.
1 5/8" headers or 1 3/4"
Go with a 75+mm TB and a 77+mm MAF.
Go small combustion chamber on the heads to bring the compression up. You can mill even more to bump compression
CAI that draws from the fender
2.5" cat-back exhaust system

I don't know what's on your car already, but if you really want to do it right, the supporting parts are many. You'll need to address the fuel system. A 255 LPH pump is plenty. Adjustable fuel pressure regulator is a nice to have item.

Going down the rabbit hole of non-engine related supporting mods that I feel are necessary would take forever. So, I'll stop here. Good luck with your build.

 

[94RioRedSnake]

Do you think there are any concerns that the 190cc head is too big for the 302? I go back and forth and I'm not sure if I would be better suited by the 170cc head. At the end of the day this is a street car so part throttle power and throttle response is very important. I probably should call a cam expert like the guy you mentioned and see what he thinks about those size heads on a 302 with one of his cams.

For non-engine mods I've got subframe connectors going on next week, and hopefully by the end of the year I'll have coilovers on all 4 corners along with a panhard bar and beefed up rear lower control arms. Then I might consider getting my feet wet with tuning before I spring for engine mods. Thanks for the response.

 

[2000xp8]

Best I've seen in person to date was about 360rwhp (I think, it's been a while, regardless it was close to that number). Not my car, a friends, at another friends shop.

Custom cam
rpmII intake
75mm tb
80mm mass air
30lb injectors (no need to exceed that, 30's will go well into the 400's NA).
afr 165's.

Tuning is not going to be the make or or break it with power. I'd expect little to no gains from it NA.

You are likely going to give up low end to get the max power.

With all that said, IMO (from someone who chased as much power as possible at the time on a stock shortblock,) it's a mistake.

The goal should be a perfect running and driving car with the best power average across the rpm band.

I'd shoot more for like 325rwhp.

 

[25thmustang]

It sounds like you want 350-375 hp, so in the lower 300s to the tire? Solid aluminum heads, I agree on a custom cam, you could probably stick to your Cobra intake and do some work to it, support it with TB, MAF, 24lbers will probably do it, but 30s definitely will, full exhaust and power wise your there. I agree 100% on keeping it street friendly verse going for more power and losing manners.

 

[Mustang5L5]

11R with cobra intake might be a tad be choked off. If peak HP is his goal he'd have an easier time with a aftermarket manifold IMHO.

 

[FastDriver]

I definitely feel a cobra intake will hold you back.

And, I guess I'd like to explain my reasoning on the injectors. It's fairly easy to compensate for larger injectors in the tune, but it's hard on injectors and fuel pumps to overpressurize systems in order to compensate for injectors that are too small. Eventually, it's impossible to compensate. So, you're better off starting off with injectors that are not working hard to make the power you're looking for. Now, Ford uses 19 lbs injectors on a stock mustang that makes around 190 rwhp. They use 24 lbs injectors on stock cobras that make about 230 rwhp. The chevy LS1 engines made 280-310 rwhp and used 28 lbs injectors. The chevy LS7 makes around 430 rwhp and runs 39.9 lbs/hr injectors.

I often like basing my decisions on what OEM engineers are doing. And the cars I'm describing, all n/a from the factory, are using ~1 lbs/hr of injector for every 10 rwhp. That's just a ballpark for V8s. That gave me my initial 36 lbs injector recommendation.

Now, I've got a nice little excel spreadsheet that does all the injector math for me, and using the 0.45 BSFC rule of thumb for n/a motors, and using the 15% drivetrain loss, 375 rwhp translates to 441 crank hp. That leads to a fuel requirement of 198 lbs/hr, and that's 24.8 lbs/hr per cylinder. If you want to keep that duty cycle below the 85% rule of thumb at stock fuel pressure, then you'll need 29.2 lbs/hr injectors. Therefore, do not go less than 30 lbs injectors.

Here's the thing, guys run perfectly fine with 42 lbs/hr injectors and they'd leave you a lot of room to grow. So what if you don't use all of the duty cycle?

 

[FastDriver]

You know, I may have misunderstood your power goal, because I thought you were speaking in terms of rwhp. 350 at the crank is a snap, and yes, it could be done with a cobra intake and 24 lbs injectors. However, I still don't think the 11R 190s and the Cobra are a match. You can save quite a bit with a smaller TFS 170 in that case.

Do you think there are any concerns that the 190cc head is too big for the 302?

Nope. I used to, but that theory is dead to me after all of the successful builds I've seen with up to 205cc heads on a 302. The whole intake tract should be matched to work as a team. That's why a Cobra intake a 190cc 11R heads doesn't make a lot of sense. If you went with lower flowing heads, like AFR165s, then a cobra intake makes more sense. In then end, your custom cam will be spec'd to make up for flow at the top with more duration, or it will be more mild and yield better street manners with the higher flowing gear. Making power the 2nd way is easier.

Thanks for the response.

Sounds like you are on the right path for a really fun car.

 

[94RioRedSnake]

Thanks everyone. It sounds like I have a few routes. If I aim for ~300 rwhp I might be able to use my stock injectors and ported cobra intake. If I aim for ~350 rwhp then I'm definitely looking at replacing injectors and probably intake, along with all of the other supporting mods. Because the heads are the same price in either scenario (11r 190 vs 170) I don't think there will be a ton of difference in total cost between the two when you account for all of the necessary mods. Heads, cam, intake ported or bought, MAF, tb, injectors, fuel pump, full exhaust, quarterhorse. So I don't see this is as much a financial decision as it is a streetability decision. The car will be 90% street driven. How streetable is 350 rwhp on a n/a 302?

 

[General karthief]

Does 'streetable' mean having ac, being comfortable, sitting in traffic? Sounds like you are a good planner and I think you'll get it figuared out, just remember 'keep it real and drive it' don't let it drive you.

 

[FastDriver]

Thanks everyone. It sounds like I have a few routes. If I aim for ~300 rwhp I might be able to use my stock injectors and ported cobra intake.

Uh... Yes on the ported Cobra. I made a verified 311 rwhp on a non-ported Cobra. And a big nope on 19 lbs. Maybe... just maybe it could be done with enough fuel pump and higher than stock pressure (in the neighborhood of 48 psi at 95% duty cycle, which is risky, and that would not be advisable. For 300, run 24s minimum.

If I aim for ~350 rwhp then I'm definitely looking at replacing injectors and probably intake, along with all of the other supporting mods. Because the heads are the same price in either scenario (11r 190 vs 170) I don't think there will be a ton of difference in total cost between the two when you account for all of the necessary mods. Heads, cam, intake ported or bought, MAF, tb, injectors, fuel pump, full exhaust, quarterhorse. So I don't see this is as much a financial decision as it is a streetability decision. The car will be 90% street driven. How streetable is 350 rwhp on a n/a 302?

I don't know, but I made ~320 rwhp and considered it perfectly streetable. Go big heads/ small cam.

 

[94RioRedSnake]

Uh... Yes on the ported Cobra. I made a verified 311 rwhp on a non-ported Cobra. And a big nope on 19 lbs. Maybe... just maybe it could be done with enough fuel pump and higher than stock pressure (in the neighborhood of 48 psi at 95% duty cycle, which is risky, and that would not be advisable. For 300, run 24s minimum.



I don't know, but I made ~320 rwhp and considered it perfectly streetable. Go big heads/ small cam.

Thanks. 94-95 Cobras came with 24# injectors stock (I believe) so I think that might be enough for ~300 rwhp.

 

[2000xp8]

24's are easily enough for 300rwhp.

 

[deathb4dismount]

500rwhp can be streetable with the right build. Before you set your heart on a power number, ask yourself how you want to drive the car first then start building it.

 

[FoxMustangLvr]

This is my first post, so hopefully I'm posting in the right place with the right etiquette.

I have a 1994 cobra with a stock shortblock. I've been looking at a lot of forums and it seems it's possible to get 350+ hp out of a stock shortblock n/a using the right combination. I'm really impressed with the results using the 11R 190cc heads. What other supporting mods would I need to get the most out of those heads? Obviously a new cam and maybe my cobra intake ported by TMoss would flow enough?

I'm considering learning tuning and getting a quarterhorse for a tune, or else I would take it to a pro and get it tuned. What about exhaust, cai, MAF, tb? I think I would need a new fuel pump, but are the stock 24# injectors enough? Seems like I would need somewhere between 24# and 30#. I'm trying to get an idea of what the HCI and all of the supporting parts would cost me. Thanks.

njector HP ratings: divide flow rating by.5 and multiply the result by the number of injectors. This uses a 100% duty cycle. These ratings are for naturally aspirated engines.

Example:
19/.5 = 38, 38 x 8 = 304 HP
24/.5 = 48, 48 x 8 = 384 HP
30/.5 = 60, 60 x 8 = 480 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

304 HP x .85 = 258 HP
385 HP x .85 = 326 HP
480 HP x .85 = 408 HP

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

 

[FoxMustangLvr]

Thanks everyone. It sounds like I have a few routes. If I aim for ~300 rwhp I might be able to use my stock injectors and ported cobra intake. If I aim for ~350 rwhp then I'm definitely looking at replacing injectors and probably intake, along with all of the other supporting mods. Because the heads are the same price in either scenario (11r 190 vs 170) I don't think there will be a ton of difference in total cost between the two when you account for all of the necessary mods. Heads, cam, intake ported or bought, MAF, tb, injectors, fuel pump, full exhaust, quarterhorse. So I don't see this is as much a financial decision as it is a streetability decision. The car will be 90% street driven. How streetable is 350 rwhp on a n/a 302?

Please look into Stinger PiMP or Megasquirt for DIY tuning. It's simply the best platform on a budget for the at home enthusiast with a lot of forum support to help you through the tuning process.

As far as HP goals go, torque is king on the street. Not having to rev up to or beyond 6k rpms to make HP will help keep your engine and valve train together. As mentioned earlier you shouldn't be trying to chase PEAK hp you should focus on a broad power curve (making power throughout the rpm range). That's what is best for a street car.

Building a car that makes decent HP and can rev high is not cheap nor easy, just ask @cleanLX , his E7 headed car is impressive without a doubt.

A guy that can help you tune your car with either Stinger PiMP or Megasquirt will be @a91what

 

[90sickfox]

500rwhp can be streetable with the right build. Before you set your heart on a power number, ask yourself how you want to drive the car first then start building it.

Mine is barely drivable. Throttle is like an on off switch. Makes dry asphalt feel like ice. My car is brutal at 400+ . Wider tires are a must. I have IRS so you'd think it would be easier to handle....but....nope.

 

[FoxMustangLvr]

Mine is barely drivable. Throttle is like an on off switch. Makes dry asphalt feel like ice. My car is brutal at 400+ . Wider tires are a must. I have IRS so you'd think it would be easier to handle....but....nope.

I do believe our IRS keeps the pedestrians safe when we hit boost

 

[90sickfox]

I do believe our IRS keeps the pedestrians safe when we hit boost

Yesterday, it didn't keep me from eating a curb....all bystanders were safe though.

 

[FoxMustangLvr]

Yesterday, it didn't keep me from eating a curb....all bystanders were safe though.

Oh no! Carnage pics in your thread?