Hello!

i am currently building a Bmw with a lm7 5.3l
soon its time for the engine to go in and i have to decide whatever to turbo it or not.

i want a turbo but the problem is that i will register the car with the new engine, and where i live we have some rules that i has to follow, with the weight of this car it cant have more than ~400bhp, and a minimum of ~5 psi boost if going turbo.

And that is the problem. Is there any turbo small enough to not go over 400hp at 5psi?
And it has to be on e85..

have a good day!

 

What do they do? Put it on a dyno?

 

I have to do that and show them a dyno paper

 

Put whatever turbo you want and spring the gate so it only makes whatever boost/power you need it to... print that dyno sheet...then send it to the moon

 

Where is this at anyway?

 

Sweden
yes that was my thought but i dont know if it will make much more than 400hp on 5psi boost

 

Ahh I see...

If your tuner is cool you can play with timing and boost to make whatever power you need i suppose... then actually tune it up

 

oh and i forgot, The turbo has to have a maximal capacity of 50% more power than the car should hove, so 400+50%=600hp, Can someone recomend a turbo?

 

This is a unique one. So you can have an allowed maximum of 400 wheel horsepower on a Dyno of your choice using a stock lm7? But you can use a maximum of 5 psi with a turbo that's rated at no more than 600 horsepower?

Who gets to rate the turbo max power level?

I thinks it's basically going to come down to the base horsepower rating of the n/a 5.3. Then put 5lbs to it and see what it makes. I was thinking s366 but I'm sure that turbo is going to be capable of more than 600. Can you just pick a small turbo and cam it to make the max power?

 

I would use your stock camshaft or a small aftermarket cam, like a "truck cam" to give you good area under the curve. A TBSS intake would be a good match if you can fit it. Or an LS6 intake or any other stock type long runner intake. You want to aim to keep NA horsepower at or below 290 then 5 psi will get you 400hp. Most any turbo big enough to supply 5psi to your 5.3 will give you around 400hp if you start with ~290hp NA. Just depends how bad you want to cheat and raise boost after you get your 5psi dyno!

My thought is maybe the VS Racing gen 2.5 with .96ar. which should be responsive and pretty cheap and have room to grow.

https://turbo4less.com/product/vsr-7875-g2-5-series/

Another suggestion if you want more response but are ok with a little less overall power (again at 5psi it would be about the same power and more responsive than the 7875 but 15 or 20psi it probably wont hold on as long) is the VS 70/70 turbo.

https://turbo4less.com/product/vsr-7...illet-t4-copy/

 

That 70/70 is rated at 1100 Flywheel so it's a no-go by rule of the gubment.

 

How often do they check your setup? Have one turbo for when you take it to be inspected and swap it out for a different one to drive around with.

 

Yeah, thats a tough one. I think VS is optimistic with its claims but are we talking crank or wheel horsepower? I would think this turbo is probably close to a 600whp turbo. There's a whole thread on it if OP wants to dig it up.

OP, are there any enthusiast groups near you where someone has succesfully done this? They may have better advice!

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Yep we have lots of rules. And this is only possible if we go through a special registation of the car.
So here it is, I can have max 20kw/100kg weight of the car, and the car should weight somewhere arround 1500kg so it is 300kw=402hp
And if i want a turbo the people at the inspection wants to see a MINIMUM of 5psi boost. And a turbo that is capable of arround 50% more power max so arround 6-700hp.


I have looked at the 366, You think that would be a good chooise?
My thought is to run tock cam to get the hp down. When everything with the registration is done i can change cam and so on, no one will notis

 

Its just one time now when im building the car, After that we only have normal inspections and there is zero problems

 

400 crank or at the wheels? Either way I question going to turbo in this scenario. You can make 400 crank with cam and a little bit more mods.

I've been to Sweden, so are the swapped big HP cars not able to get plates?

 

400 crank, Yes i know i can get there without turbo. But its for the registration, After that i can up the boost

Yes. Most high hp cars that not come from the factory with high hp is not registred with that power

 

Cool I have been to Stockholm and Lincoping.

If for example you run a Holley Terminator, you can control boost with it. You can run the low lb spring for the wastegate like 3 lb spring and then try to figure out how to get it to satisfy your conditions. I'd agree a stock cam 5.3 (rated at 270-290 crank) plus small boost should work. You can tune the boost level and even take out a lot of timing.

 

Oh cool, you maybe have seen stockholm open then

My plan is to use Maxxecu, But thats is probably almost the same thing
Im looking for a tuner near me now that i can talk to

 

If you have not bought the ecu get the Holley. It's very easy to use. Nobody in the states uses the ECU you just mentioned.

I've been vids of the Open, cool stuff, when was the last one about 6 years ago.

If you need to hit the #, you can put it all together and dyno and dial it in beforehand. You need a good way to control the boost. You can do it all internally with the Holley with some Mac valves and co2 or onboard air.