FI & Heads?
FI & Heads? Hi guys, I'm trying to plan out my mods. Someone told me that if you are planning to go with boost then heads aren't going to make much difference. Is that true? Should I just go cam/valve train then straight to a Maggie, or should I do the heads too?
No responses yet eh? OK, here is my opinion (which when added to $3 will get you a mocha)
No you don't need expensive heads to make HP with boost. And many of the good heads usually have a higher compression ratio than boost wants. I am running 6L heads to get lower CR (9.3-ish), where a lot of the NA motors use 5.3L heads to get 11:1+.
That said, better flow IS better flow. Anytime you reduce restriction it should equal more HP. But it doesn't make as big a difference with boost. And in general an NA motor needs to have the intake freed up, where a boosted motor needs more help on the exhaust side.
Bottom line - any heads that help you a bunch now will probably not work very well later, & vice versa.
No you don't need expensive heads to make HP with boost. And many of the good heads usually have a higher compression ratio than boost wants. I am running 6L heads to get lower CR (9.3-ish), where a lot of the NA motors use 5.3L heads to get 11:1+.
That said, better flow IS better flow. Anytime you reduce restriction it should equal more HP. But it doesn't make as big a difference with boost. And in general an NA motor needs to have the intake freed up, where a boosted motor needs more help on the exhaust side.
Bottom line - any heads that help you a bunch now will probably not work very well later, & vice versa.
More airflow through intake /heads / exhaust = less boost needed for power.
Some guys like to take their stock headed / stock intake motors and crank the boost up to say 28 psi getting whomped by a guy with a motor built to flow running 14 psi!
Some guys like to take their stock headed / stock intake motors and crank the boost up to say 28 psi getting whomped by a guy with a motor built to flow running 14 psi!
Whatever you pick up Power wise from bolting on a set of heads on your car you will pick the same amount of power on top of what youre making.Its like saying you dont need heads on a nitrous engine just spray it more.
Being that this is my daily driver I am not intending to go boost crazy. I'll keep it under 10psi.
Just curious, If I go with one of these cams and supporting valve-train mods:
Lingenfelter-
GT2-3 207/220 .571/.578 118.5 LSA
GT7 208/230 .554/.546 121 LSA(I still haven't seen a dyno sheet for this cam, but it's designed specifically for forced induction set-ups)
That should put me at around 350-375 rwhp and give me pull well past 6k rpm. How much additional hp/tq would a good set of heads add? Also, where in the curve do heads tend to add the most? down low, mid-range, or up top?
Just curious, If I go with one of these cams and supporting valve-train mods:
Lingenfelter-
GT2-3 207/220 .571/.578 118.5 LSA
GT7 208/230 .554/.546 121 LSA(I still haven't seen a dyno sheet for this cam, but it's designed specifically for forced induction set-ups)
That should put me at around 350-375 rwhp and give me pull well past 6k rpm. How much additional hp/tq would a good set of heads add? Also, where in the curve do heads tend to add the most? down low, mid-range, or up top?
I would think they would be pretty similar. They both have good LSA numbers for boost, one has more lift, the other has more duration. The bottom one might give you a tad more power because the valves aren't open at the same time for as long. (lsa) Mine is around 228/236, .575/595, 115LSA. With a 118 LSA I would pick a few more ponies, but I wanted a lopey idle.....
I'd take your heads to Accurate Engines & have Mike work on em. I forget what size chambers 243s have, but they should work for 10 psi. And he should be able to open them up & get your more power (I had hime do mine - porting, bigger valves, smooth the chambers for ~$1200 I think)
I'd take your heads to Accurate Engines & have Mike work on em. I forget what size chambers 243s have, but they should work for 10 psi. And he should be able to open them up & get your more power (I had hime do mine - porting, bigger valves, smooth the chambers for ~$1200 I think)
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Other side of the coin is that for higher compression you need better cooling of the air. I'm looking at this now. I have 11.3:1 58 cc chamber AFR's and Bob at EPP swears that as long as I run a good FMIC and meth kit I wont have any issues and will gain 140+ hp on 8#'s. This isnt the ideal thing to do but it isnt impossible either. Good heads can always been sold at a decent price to accomodate your plans as well. If your eventual plan is a s/c 2 yrs from now why hold back on the heads now.
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