Racing ST4 & Need more HP

[Rickybobby]

I race my 2007 Mustang in Super Touring 4 in NASA. and I’m changing tires so I can get more HP per ST4 regulations.

I’m looking to make 310rwhp in a flat as possible curve throughout the rev range. (4K & up) Right now I make around 280 with an open exhaust & tune (The tunes not for peak but for a flat HP curve) but no more mods. What are some modifications I can do to achieve this without hurting my reliability?

Thank you!!!

 

[AHaze]

Do you already have long tube headers? If not, those and a set of mild-ish cams should get you there at the peak. Not sure you'll be happy with the gains down at 4000 RPM though.
If that doesn't do it, I'd say you're the perfect candidate for a stroker.

 

[Rickybobby]

Do you already have long tube headers? If not, those and a set of mild-ish cams should get you there at the peak. Not sure you'll be happy with the gains down at 4000 RPM though.
If that doesn't do it, I'd say you're the perfect candidate for a stroker.

What long tube headers do you suggest?

 

[Midlife Crises]

Bang for the buck. If the class allowed it, a striker will give you the potential for more torque through the low and mid rev range. Mild cams could help a striker also. Long tube headers like Kooks will always help but you prodadly won’t be able to run them open.

 

[Dino Dino Bambino]

Do you already have long tube headers? If not, those and a set of mild-ish cams should get you there at the peak. Not sure you'll be happy with the gains down at 4000 RPM though.
If that doesn't do it, I'd say you're the perfect candidate for a stroker.

A stroker for a mere 310rwhp?
@Rickybobby you can reach your goal by adding charge motion delete plates, underdrive pulleys, and LT headers. At that power level you don't need to crack open the valve covers (see my sig).
What's your open exhaust set up?

 

[Rickybobby]

A stroker for a mere 310rwhp?
@Rickybobby you can reach your goal by adding charge motion delete plates, underdrive pulleys, and LT headers. At that power level you don't need to crack open the valve covers (see my sig).
What's your open exhaust set up?

No cats, no muffler just open exhaust.

 

[AHaze]

A stroker for a mere 310rwhp?

I realize a stroker is not required to get to 310 but they want to move the entire power curve up by 30rwhp. Admittedly, I don't have any dyno sheets in front of me but from what I recall most bolt on stuff doesn't help much down at 4000 rpm on a stock displacement motor. Long tube headers probably being the biggest exception.

 

[Dino Dino Bambino]

No cats, no muffler just open exhaust.

What long tube headers do you suggest?

You could take the budget route with Pacesetter or even eBay LT headers.

I realize a stroker is not required to get to 310 but they want to move the entire power curve up by 30rwhp. Admittedly, I don't have any dyno sheets in front of me but from what I recall most bolt on stuff doesn't help much down at 4000 rpm on a stock displacement motor. Long tube headers probably being the biggest exception.

The CMDPs and UDPs will help the bottom end a little but the biggest HP/TQ gains from those are from 3000rpm upwards. The best choice of LT headers are the 1-5/8" full length versions as these produce the biggest TQ gains in the midrange as well as a decent HP gain at the top end.
The trick here is to maximize the area under the torque curve as much as possible while staying within the rwhp limit for ST4 racing i.e. minimum 12lb/rwhp. Therefore at a race weight of e.g. 3600lb it's 300rwhp.

@AHaze your tune will need to be adjusted for the above mods but looking at the A:F ratios on your dyno graph, it looks like it needs adjusting anyway as the engine's too rich from 4000rpm upwards (12.6-13.0 is optimal).

 

[Midlife Crises]

If you stroke it you won’t have to rev the guts out of it. You will have more power through the entire operating range.

Dino Dino Bambino. Good catch on the A/F ratio. Maybe the tuner is using fuel to cool the engine. I’d say turn up the boost for that fuel curve.

 

[AHaze]

@AHaze your tune will need to be adjusted for the above mods but looking at the A:F ratios on your dyno graph, it looks like it needs adjusting anyway as the engine's too rich from 4000rpm upwards (12.6-13.0 is optimal).

Not my dyno graph but good catch. I missed that completely.

 

[Oliver Vigil]

I am not too familiar with the regulations of your class, but this is what I would recommend if allowed: aggressive cams, a nice set of ported heads, shorty headers, and some sort of intake to support better airflow. You would easily be able to reach your 30hp goal while retaining reliability. Put some timing into her, they love it, and you could even consider running a colder spark plug to support the above modifications. Most of my tuning experience with these engine are boosted, but I am quite certain you'd love this combo. I doubt you will be able to see a 30hp increase in the low end without super charging or increasing displacement. Best of luck!

 

[Rickybobby]

Thanks for all the advice! Keep it coming!!!!

 

[Rickybobby]

Just bought these headers…Did I make a mistake?http://rover.ebay.com/rover/1/711-5...uAGrJ6FRQ6&var=&widget_ver=artemis&media=COPY

https://www.ebay.com/itm/1746207967...uAGrJ6FRQ6&var=&widget_ver=artemis&media=COPY

 

[RED09GT]

You could try advancing the cams. That would involve taking the timing cover off and using the TFS crank gears. Cost wise, it would be pretty low and closing that intake valve a bit sooner-maybe 4-6 degrees or so could be worth a decent amount of torque. Best part is if it doesn't give the gains, you can add a bit more cam retard in the tune and go back to similar timing events as stock.
The comp SPR cams lose virtually no torque due to the fact that they are installed on a 102 degree ICL vs 110 ( I have forgotten exactly what it is) of the stock cams. Even with the much larger timing events of the comp cams, they still close the intake valve at a similar time to what the stock cams do and that preserves torque production.