Toyota MR2 Message Board - View Single Post - Getting power from a 5SFE without forced induction

mrturrari · 06-30-2008, 12:55 AM

KBrew,

I don't know if the 93 would really be an upgrade It's hard to tell because they have less duration but more lift. That's a little better for turbo charging but for NA the 91s might have a very slight advantage. The torque curves look almost identical from what I have seen so I truthfully don't know. Adjust your valve clearance on the tight side to get a little more lift. lol

So in your case since you have to live with the stock cams and your not really worried about loosing low end, I would try 1-5/8" primaries and then make them shorter then usual, maybe 24-28". I have 1-5/8" with 28" long runners on my car right now and it does improve the torque in the 4000-4500 range even before I upgraded cams. Another option would be to pick a higher torque peak, say with 1-3/4" pipes, and use longer runners, maybe 28-32", to pull up the curve below that. That may not be as effective though. There is still so much in header building that is going to be trial and error. The formulas just get you in the ballpark.

06-30-2008, 12:55 AM	#10 (permalink)
mrturrari I <3 my 5sfe Join Date: Mar 2005 Posts: 404 Thanks: 2 Thanked 90 Times in 58 Posts iTrader Rating: (0/0% )	KBrew, I don't know if the 93 would really be an upgrade It's hard to tell because they have less duration but more lift. That's a little better for turbo charging but for NA the 91s might have a very slight advantage. The torque curves look almost identical from what I have seen so I truthfully don't know. Adjust your valve clearance on the tight side to get a little more lift. lol So in your case since you have to live with the stock cams and your not really worried about loosing low end, I would try 1-5/8" primaries and then make them shorter then usual, maybe 24-28". I have 1-5/8" with 28" long runners on my car right now and it does improve the torque in the 4000-4500 range even before I upgraded cams. Another option would be to pick a higher torque peak, say with 1-3/4" pipes, and use longer runners, maybe 28-32", to pull up the curve below that. That may not be as effective though. There is still so much in header building that is going to be trial and error. The formulas just get you in the ballpark.