evildky Posted November 13, 2005 Share Posted November 13, 2005 ok so I wetn to the dyno yesterday and the results were less than impressive more to come on the details, but the power really dropped off 5000 rpm, I am currently running a stock junkyard turbo motor P90A and all, I've heard around here that the N42 with mechanical lifters is the way to go, but I can get ahold of an E31 cheap and go to oversized valves and internaly lubricateded cam towers, any thoughts on doing this? with an .020 overbore, dished pistons and 2mm headgasket it yeids an 8.11:1 ratio which I would think is plenty safe? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 14, 2005 Share Posted November 14, 2005 you want to go with an E31 head to move the power band higher in the RPM? I dont' think just the head swap would do that, better to do flow work on the P90. Even if it's the hydraulic head that should have NO effect on power until after 5500-6000rpm. Anyways, no matter what you do, the stock turbo does start to fall off pretty low in the rpm range. My power has always peaked at around 5000rpm, torque curve is flat from around 3000-4000 rpm then falls off sharply. If you look around this curve is VERY typical on the stock T3. If it were me, I'd stick with the head you have. A cam swap, larger exhaust (if you aren't already 3" mandrel), head work, or upgraded turbo can all give you higher rpm power. Quote Link to comment Share on other sites More sharing options...
evildky Posted November 14, 2005 Author Share Posted November 14, 2005 where the power peaks isn't the problem the problem, the engine wasn't wanting to rev past 5k, it just really had no power up there, I was just wanting to go with a mechanical head as popular opinion around here is that you have to if you want to rev past 6500, and the N42 is about as hard to find around here, I know where I can get an E31 today, or maybe I just need to hold out for the N42? Quote Link to comment Share on other sites More sharing options...
GrayZee Posted November 14, 2005 Share Posted November 14, 2005 I can't claim to understand the science of combustion chamber shape and detonation, but I had the understanding that the older heads were kind of outdated in that way. Something to consider anyway if you want to use a older head. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 15, 2005 Share Posted November 15, 2005 I can't claim to understand the science of combustion chamber shape and detonation, but I had the understanding that the older heads were kind of outdated in that way. Something to consider anyway if you want to use a older head. agreed 100%. The debates on the round combustion shape heads (N42, E31) vs. hemi shaped combustion chamber heads (P90) go on for days. If it's just a matter of you wanting to get rid of the hydraulic lifters, then go with the P90 non hydraulic head, which was also found in many of the L28 turbo motors factory stock. I would not go with that E31 head. Not saying you can't, just saying I wouldn't. P90 non hydraulic heads can still be found and in the $75-100 range last I looked. I honestly don't think it's going to make a difference. As I mentioned, everyone who has ever had a stock turbo motor, or even upgraded one, but still on the stock T3, has found that torque falls WAY off after 4000-4500rpm, and hp falls off sharply by 5000-5500rpm. I don't think I've seen ANYONE on the stock T3 making good power above 5500. It's not the head, it's the turbo. You may have some other issues that need adressing, you may be running way lean on the top end. The hydraulic head supposedly has NO issues compared to a non hydraulic head until at least 5500rpm, up to that point it shouldn't be costing you any power. Quote Link to comment Share on other sites More sharing options...
spork Posted November 17, 2005 Share Posted November 17, 2005 you could also just convert your p90a head to solid lifters. Grab a scrap head from someone and like $36 for thread insert sleeves and you're converted. You will need a different cam as the hydraulic one will not operate properly in a non hydraulic head. The cam lobe ramp profiles are different. If you don't mind me asking, are you still running the stock turbo, and what boost level? Quote Link to comment Share on other sites More sharing options...
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