How much power from the stock pistons and rods

[axaQ42]

I think it wont be such a problem to share it

[AlfaJack]

We would appreciate it

[axaQ42]

I will upload it somewhere when i get it on the computer

[#84]

To go back to the original question, I can mention that the original piston weights over 600 gram, I think it is in the region of 630 g. As a comparison the 2 mm bigger SAAB/Opel 2 l. turbo piston weights only about 350 g.

So, as mentioned: Torque and boost is no problem, but rpm is. I have my rev limiter on 7000 rpm, but don't run it that high very often.

[AlfaJack]

I can quite happily limit it to 6500, should be quick enough by those revs with the planned parts.

[#84]

Then I would spend the money on parts that really makes difference in performance - unless your budget is unlimited

[AlfaJack]

Then I would spend the money on parts that really makes difference in performance - unless your budget is unlimited

These should make the difference?

I am planning a GT28RS or similar, tubular manifold, bigger injectors if need be, full metal IC (same size and shape as the original as I don't want to modify the piping too much), Walbro fuel pump and a proper mapping session on a rolling road. I would love to pull the engine out and do this as a long term project that is not too feasible.

Or are you talking about much bigger turbos? I don't want an overly laggy car if I can avoid it.

Budget is certainly not unlimited!!

[#84]

Where to spend the money is a good question. Based on knowledge and experience:

1. Removing pre-cat = More or less for free
2. A clever map (unlike most maps that are copies of each other) = For free or very expensive..
3. A free flowing exhaust system. Race cat not a must. This is the base for all tuning since you otherwise experience high exh. temps. = ?1000+
4. At least a foam panel air filter = ?50-
5. Uprated fuel pump. No fun, but a must. = ?150
6. Uprated fuel pressure Gives up to 20 % more flow than original = For free
7. A modern turbo. Forget everyhing with T3 in its name. That is my opinion. Most bang for the bucks is the today old Mistubishi TD04-19T from Volvos. = ?500-750
Otherwise a IHI or Mitsubishi twin scroll, but that complifies everything = ?1500-2000 in total
8. A clever exh. manifold. I would say a small volume 4-2-1 design in the power range we talk about = ?450-600 (depending on material and turbo flange)
9. Intercooler. Based on the car's design a water based system could be a good solution, but a big on ein the front would probably be the safest choice = ?300-1000
10. Adjustable pulleys = ?300-450
11. Camshafts = ?700->
12. Stronger head gasket = ?150
13. Forged pistons, maybe = ?600->

Ok, that is how I should do. I suppose there are "some" other opinions in this forum...

[Juan AR155Q4]

8. A clever exh. manifold. I would say a small volume 4-2-1 design in the power range we talk about = ?450-600 (depending on material and turbo flange)

I can't figure out how could you fit something like this in the small place left between engine and radiator.
Do you have any pic illustrating this?

[#84]

I haven't fitted it - yet, but it is smaller than the traditional Supersprint "spaghetti"-manifold. I will ask a friend about a picture of his installation. I don't think he is on the forum. I'll be back.

[Evodelta]

4-2-1 turbo manifold? Are you sure?



Edit: Unless you mean a twin entry turbo??

[1NRO]

4-2-1 manifold would be for a single scroll turbo martin

[1NRO]

Hi guys,

How far can you go with power from the original pistons and rods. I am considering upgrades this year and want to have a good safety zone. I would like to have somewhere between 300-330bhp.

Also, when upgrading the pistons and rods, what does an after market piston allow that the stock wont? Is it less weight or more strength?

Thanks.

Some forged pistons come with improved power potential, higher CR for instance. Manipulation of the combustion/charge is possible too along with assisting the exhaust stroke. A reduced friction from suitable rings again assists in potential power. Changes in geometry will lend a helping hand to the pistons, less side loading for example. Other changes (admittedly small) are a consequence of this. Changes to the squish pads help too. There are loads of areas that can be tweaked for improvement over oe. Pretty numb thing an oe piston. A quality forging isn't a slack fit, thats complete rubbish. Lesser quality forged pistons have a bigger piston to bore clearance true but not quality ones. A massive saving in weight is possible which helps a number of areas, for instance rpm potential and response. A properly speced and installed forged piston offers a LOT of improvement, just not easily available

Nik

[#84]

Evodelta: Maybe you understood the concept, otherwise I will try... The concept is that 1+4 and 2+3 are connected shortly after the exh. port so that only two pipes enters the turbo inlet. So, if you have a twin-scroll turbine it would be a 4-2 manifold instead. The purpose is to minise volume, with increased pulse efficiency in the low end.
/A

[Evodelta]

Evodelta: Maybe you understood the concept, otherwise I will try... The concept is that 1+4 and 2+3 are connected shortly after the exh. port so that only two pipes enters the turbo inlet. So, if you have a twin-scroll turbine it would be a 4-2 manifold instead. The purpose is to minise volume, with increased pulse efficiency in the low end.
/A

I wondered if that is what you meant, but I've never heard of one before on a turbo engine, common on N/A of course.
Do you have a picture of such a thing? Is it a good idea to mix the pulses from two cylinders in one pipe?

[Evodelta]

I can't figure out how could you fit something like this in the small place left between engine and radiator.
Do you have any pic illustrating this?

If you have two pipes instead of four you will need less room no?

[#84]

It is used in cast iron OEM manifolds, like the SAAB 9-5 and old 9-3, not the GM engine. Probably also in many other modern engines. I have asked my friend for a picture and he should look for a picture or get one, but it could take some days since he was out of workshop/work for some days.

You will gain som space in the engine compartment, which of course is positive, but the major argument is less volume in the manifold itself.

[arjunior45]

You mean this one?

[#84]

Yes I do.

And here comes the pictures from MrNick on this forum. As he says to me, there are certainly a lot of critics that could be rised against the diffrence in pipe length and maybe also the design. But it is proven to work very well on both Cosworths and Integrales etc. The last time I asked about the price, it was ?450 for std steel and ?550 for stainless steel.

And besides. There is a reason to why SAAB has that design. It is probably the best 4-cylinder design you can cast. The higher rpm you optimise at the less important is it to keep down the volume and the more important it is to optimise flow properties, but the design shown is used on many high performing Deltas and Cosworths - where Spaghetti-manifold has been tested as well.

[arjunior45]

I found these pictures from the Saab 900, 9-3 and 9-5 exhaust manifold!
I do not think it's the same as the one used from MrNick, am I wrong?

[AlfaJack]

was ?450 for std steel and ?550 for stainless steel.

This seems like a pretty good price to me

[1NRO]

I'd rather stick with the standard cast iron bomb proof manifold, it's easy to bolt on an aftermarket thats no better or worse. To actually do anything worthwhile a 4-2-1 manifold needs length (as do all manifolds worth the money) a perfect example in the pic below. There are a bundle of reasons to use this style but imo the main objective for the guys that can is to target two harmonic ranges, the production ones in the pics above are aimed at a level pretty much fitting their standard level. Start pushing the power up and the design changes.

[#84]

That is a cool design!

First: The SAAB manifolds are in principle the same as MrNicks if you reconsider the turbo location.
Secondly: 1NRO, you are perfectly right about the harmonics and that is the ultimate way to achieve the highest scavegning efficiency. But - the volume is enormous and volume kills respnse and low end performance. A bit up in the rpms performance is normally limited by engine strength (head gasket, bolts etc) or injector size / pump performance - at least on road going cars. So, with a mild turbo application (high CR) like CART or turbofication of NA engines, the design you show would be good. But for a Q4 engine used on road, it has no cahnce in overall performance.

Then: While mentioning SAAB. The head of research a few years ago is a real turbo expert, running BoostBusters as a private business. He built a system like the one in the picture on his E30 M3 EVO and if I remember it correctly the turbo was so far from the engine so it basicly was under the floor.....

[1NRO]

I look at changing original spec as a search for power, how far you go determines the most suitable specification, true enough the one shown it pretty high end.

The method is sound but not really much of an improvement over what is already there, they designed it (saab stylie manifolds) to compliment the package and all it's production restrictions.

I know the volume is huge but I'm not thinking about manifold volume, even those long pipes will fill in a nano second, there is a turbo at the end of them afterall.

Nik

[#84]

Nik, That s almost poetry: "..., there is a turbo at the end of them afterall."

But fitting such a manifold in a Q4 is a job on Houdini's level, or worse...