soya_sauce Posted June 27, 2005 Report Share Posted June 27, 2005 hey just looking for some suggestions on milking a few more ponies out of a realatively stock engine. THe plan so far is too rebuild and balacne the bottom end, have the heads rebuilt and hop up the intake and exhaust systems on the car. im curious about bumping up the compression. What s the preferred method? having the heads shaved or swapping out the pistons? as well whats a safe compression ratio to run? As for heads, are the stock vavles adequete or should they be swapped for something a little larger. THe goal is to try and achieve somewhere around 260hp. any help would be greatly appreciated. thanks p.s the engine is out of a 91 lumina and i beleive it's not a an interence engine (correct me if im wrong) Quote Link to comment Share on other sites More sharing options...
88Regal Limited Posted June 27, 2005 Report Share Posted June 27, 2005 Another Aaron! Quote Link to comment Share on other sites More sharing options...
Aaron Posted June 27, 2005 Report Share Posted June 27, 2005 heyjust looking for some suggestions on milking a few more ponies out of a realatively stock engine. THe plan so far is too rebuild and balacne the bottom end, have the heads rebuilt and hop up the intake and exhaust systems on the car. im curious about bumping up the compression. What s the preferred method? having the heads shaved or swapping out the pistons? as well whats a safe compression ratio to run? As for heads, are the stock vavles adequete or should they be swapped for something a little larger. THe goal is to try and achieve somewhere around 260hp. any help would be greatly appreciated. thanks p.s the engine is out of a 91 lumina and i beleive it's not a an interence engine (correct me if im wrong) I decked my heads to get better compression personally, but any method works. On my new motor, I'll be using new pistons, as the most you will ever get from a head deck is a half point, and that is pushing it. The stock valves are adequate, and bigger ones cannot fit into the head as they are already extremely close together. 260hp is not at all unrealistic, contrary to popular belief. I got almost 265hp out of mine, although it was modified quite a bit, but still not tuned, and still quite a bit untapped. Some other things I would do is the cam timing adjustments, these have huge gains for minimal amounts of work. I think a 6* retard on the exhaust, and a 6* advance on the intake, has given the best gains to date. Also, a 96+ intake manifold swap will help tremendously. All of this, with the other bolt ons and tuning, and 260hp will be easy. Quote Link to comment Share on other sites More sharing options...
sonyman87 Posted June 27, 2005 Report Share Posted June 27, 2005 http://www.fastfwdperformance.com chip poly. dogbone UD pully with a good exaust and intake will get your 3.4twincam into the mid 15s. P&P upper and lower intake manifolds + gasketmatching them will help another .1-.2 tenths. Altering the timing on this motor dosnt actualy make more power it only lowers the powerband so your peak HP is around ~4k rpms and not ~5krpms. with aarons suggestion of timing you will hit a wall at 5,800rpms and it wont want to go much higher. this is bad if you an auto. please no flameing on this comment you can also try an eRam intake. http://www.electricsupercharger.com i used one of these + chip + exaust + UD pully + 160* stat + poly. dogbone and with some driving skill and 22psi in the front tires pulled a 15.1 last summer. its cruital that you hold 2nd gear to just under fuel shutoff before manualy shifting. makes a .2-.3 second difference. after july 17 i will be able to tell ya how much a difference exaust cutouts make and tires 10% to small make. Quote Link to comment Share on other sites More sharing options...
soya_sauce Posted June 27, 2005 Author Report Share Posted June 27, 2005 so when you decked your heads how much did you shave off? whats your compression ratio sitting at right now? im curious to know what people have done for exhaust as well has anyone had custom headers made up? Quote Link to comment Share on other sites More sharing options...
GP1138 Posted June 27, 2005 Report Share Posted June 27, 2005 im curious to know what people have done for exhaust as well has anyone had custom headers made up? Look a couple of posts up. Quote Link to comment Share on other sites More sharing options...
Aaron Posted June 28, 2005 Report Share Posted June 28, 2005 Altering the timing on this motor dosnt actualy make more power it only lowers the powerband so your peak HP is around ~4k rpms and not ~5krpms. with aarons suggestion of timing you will hit a wall at 5,800rpms and it wont want to go much higher. this is bad if you an auto. Altering the timing does a lot. And a 13* retard, or 6/6, does make more power, significantly more. And it moves the power curve up if anywhere, not down. With my suggestion of timing, it has been tested twice using Kohburn's tool to get EXACT increments, you will get an identical low end, with good idle, and much more top end power, pulling right to 7000rpm. I'm not flaming you, but this is entire point of the cam adjustments. There are adjustments you can make to make it an all low end motor, but they deal with advancing the exhaust cams. I built a set of tuned equal length headers for the white car in my sig, of which Tony, aka 5speedz34, now owns. IMHO. they added a lot of power, and was the best mod done to the car and I think they were worth every penny and minute. From our best knowledge, this is the only set of working headers on a 3.4l w-body. Milzy's manifolds don't count. Quote Link to comment Share on other sites More sharing options...
timg Posted June 28, 2005 Report Share Posted June 28, 2005 Aaron, What was your highest WHP? This may come off a bit ricey, but I have an excel spreadsheet that I made to estimate crank HP based on a few different stock auto dynos. The 5 speed dynos I have seen were all a bit higher than the auto dynos, but I don't think any were stock. IIRC, your dyno was around 222 whp. On an auto, the drivetrain loss seems to be around 21% or 44 hp (for both the NA 3.8 and the 3.4 DOHC- assuming that all of the motors have stock levels of crank horsepower and GM didn't overrate the car). The high estimate of 222 whp is 281 crank hp (% based) and the low is 266 crank hp (delta based). The average of those two would be 274 crank hp... Pretty darn good and definitely backs up a claim of around 265 crank horsepower. Others may dispute my #'s, and if they do I'd like to hear it. I wouldn't mind updating my spreadsheet to more accurately reflect reailty! Milling heads- the rule of thumb for thicker headgaskets is that every MM drops compression by a point. I would assume that milling a head by a millimeter would increase compression by roughly a point. Tim Quote Link to comment Share on other sites More sharing options...
Aaron Posted June 28, 2005 Report Share Posted June 28, 2005 Aaron, What was your highest WHP? This may come off a bit ricey, but I have an excel spreadsheet that I made to estimate crank HP based on a few different stock auto dynos. The 5 speed dynos I have seen were all a bit higher than the auto dynos, but I don't think any were stock. IIRC, your dyno was around 222 whp. On an auto, the drivetrain loss seems to be around 21% or 44 hp (for both the NA 3.8 and the 3.4 DOHC- assuming that all of the motors have stock levels of crank horsepower and GM didn't overrate the car). The high estimate of 222 whp is 281 crank hp (% based) and the low is 266 crank hp (delta based). The average of those two would be 274 crank hp... Pretty darn good and definitely backs up a claim of around 265 crank horsepower. Others may dispute my #'s, and if they do I'd like to hear it. I wouldn't mind updating my spreadsheet to more accurately reflect reailty! My highest was 218whp and about the same torque on my white Z34. On my stock one, the red car, it made 178whp/186wtq. I believe the 5-speed has less power draw, and the dynos back this up, but how much is unknown to us, I am guessing 15-18%. This dyno is good, but I was hoping for a lot more with my white car, and I think it was capable of it, but we will never know. Quote Link to comment Share on other sites More sharing options...
z34_nut Posted June 28, 2005 Report Share Posted June 28, 2005 That HP does sound a right, tim. According to the dyno my car is rated at 219 whp, and crank power was estimated at 260-265. I would love to have so much time on my hands to pull it out and flog it, but its just so unreasonable. Certainly non of the cars at my old school were difficult to yank the motor out from between the framerails. Quote Link to comment Share on other sites More sharing options...
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