To Turbo or not to turbo

[igotbank]

So I have a 85 m535i(non cat) i purchased through this site and i want more power. Thing is i'm not sure if I want to stay naturally aspirated or not. Can anyone tell me the gains from an aggressive cam and exhaust? I'm toying with the idea of turbo as an alternative to doing a motor swap. What i need to gather is turbo realiability-as it's my daily driver and actual hp cause i like to get there fast. I've owned a lot of bmws, no turbos though. I know there are a few TCD 5s out there how are they? I've purchased misc e28 items from todd so giving him 5k isn't an issue. can anyone vouch for his turbo work/products. Everything looks polished and nice but i'm looking to get real world feedback. If anyone has any alternative ideas please hook a guy up! thanks in advance

[pdx 528e]

You might want to post this in the Forced Induction forum. Also, it sounds as though your car has the dirty high compression motor. I am assuming this because it lacks the catalytic converter. In this case, you won't be able to yield as much of an increase in pressure without changing the compression ratio by changing pistons.

[Jeremy]

With low to moderate boost you'll get great power and fantastic reliability. However, you mention you have the non-cat m535i. You have the high compression motor then? That makes things a bit trickier, standalone engine management, lower compression pistons, or at least a thicker than stock MLS gasket might be in your future if you really want to go turbo.

Jeremy

[igotbank]

PDX: thanks for the advice never thought the non cat motor would be undesireable for turbo.

Jeremy: so you like todd's(TCD) products, i see you have two. Did he install also? How or what determines low or moderate boost? Is it turbo size? and did you add a more aggressive cam?

[Justin_FL]

OK, I moved this thread over here into FI--- doing this is better than cutting & pasting into a new thread and starting over. That would confuse people

[M. Holtmeier]

Boost level depends on what your wastegate setting is. You can change spring rates to achieve a particular boost level. As Jeremy mentioned using stand alone engine management, such as Megasquirt, you can control boost electronically. The turbo's in Todd's kits are matched very well to engine application. The sky's the limit really. I am pleased with the setup I got from Todd.

[Jeremy]

Boost level depends on what your wastegate setting is. You can change spring rates to achieve a particular boost level. As Jeremy mentioned using stand alone engine management, such as Megasquirt, you can control boost electronically. The turbo's in Todd's kits are matched very well to engine application. The sky's the limit really. I am pleased with the setup I got from Todd.

Well, that's not exactly what I meant. The standalone gives better control over fuel and timing, which is required when running boost through a high compression motor. Modified Motronic isn't really the best idea in that case.

Moderate boost on a low compression M30 IMHO is 10-15psi. On the high compression motor I suppose 6 psi or so would be very safe. Todd would know better than I, have you talked to him at all?

Jeremy