View Full Version : How much power from the stock pistons and rods
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.
OEM conrods - I know engines with standard conrods which have over 500 hp (with forged pistons), one of these was used in the competition. Can not provide the torque figure though.
Forged pistons/conrods are lighter and have more strength. There is however diferent treatment of the word "forged" on the net.
Type of metal matters in forging also. Some expand more than others, therefore you need to take that into consideration while boring the block/ordering the pistons/rings, and ultimately then driving the car.
Varypodaros
26-03-10, 17:36
I think that it's a little bit risky to have 300 bhp with normal pistons. I think that a nice and safe horsepower to have is 260 bhp.
If you like to have 300bhp or more I think that it's better to use forged pistons. the normal rods are Ok even at 450 bhp or even more!!!
the forged pistons allow less weight and they are more resistant at the high temperatures...
I have to say that here in Greece is a Delta Integrale with normal pistons and 350 bhp but it has:
-stock cams
-stock head gasket and head.
-stock rods
-stock pistons
-holtzer type exhaust manifold with 42mm diameter and not 38mm
(http://www.hfintegrale.gr/smf/index.php?topic=20.0)
-metalic exhaust gasket
-Εxternal Waste gate Turbonetics Evolution.
-exhaust 84mm Down Pipe to the end with one cilenser
-stock Turbo Τ35 with 360 Thrust.
-Ιntercooler custom PMC 640χ340χ70.*
-Σωληνώσεις αέρα αλουμηνίου και κολάρα σιλικόνης.
-aluminium pulleys custom made.
- Samco pipes.
-oil radiator Setrab,
-custom made maps for the ecu
-stock fuel injectors 384cc.
-Walbro 255lt fuel pump.
-air filter BMC.
-blow off valve Greddy Type-R
http://img46.imageshack.us/img46/3086/dsc000301rit4.jpg
321 hp and 42kg at 1,8 bar
352 hp and 44,7 kg at 1,9 bar
:icon_cool:
It is how you look after something which makes it last, if you want to go for high power on stock rods and pistons then do so carefully and in an intelligent manner - cool intake charge, proper map (ditch your chips) and cap the RPM.
Would I recommend it? No, but I have made it work, I did it 'cause I had nothing to lose and had other things to prove.
Cast alloy is lighter than forged. Traditionally cast pistons fit the bore better (less expansion to worry about) so can make more power, just more unreliably.
That isn't to say that forged pistons are heavier, quite the opposite. Because it is a much stronger material you can make a stronger piston using less of it.
arjunior45
27-03-10, 15:24
The very first FIAT Uno Turbo had oem forget pistons. Those after the first generation had 'normal' one.
I would go for
- forget piston of a well known brand and balanced them at +-0,10 gramms {not the 5 gramms for the oem pistons}. It's a 'job' that noone but you can do that!!!
- balance the oem rods {with the 'new' pistons installed} and polished them like glass/mirror. But first check them if they are ok or if there are any signs of worn or distortion. Replace any faulty one.
and
- polish the oil drain channels.
It will be nice to polish and balance the crankshaft too.
Power is not the issue, you could blow pistons at stock power. Tuning, and mainly RPM is the major consideration.
The very first FIAT Uno Turbo had oem forget pistons. Those after the first generation had 'normal' one.
.
What do you call "the very first Uno turbo"? Ive pulled many engines apart and never seen a forged piston.
OE cast pistons are lighter than forged and fit the bore better (less expansion to worry about) so will make more power, just more unreliably.
Are you sure that's not a typo? Forged pistons are generally designed to be lighter than OE. Your comment would suggest there is only a single option (that is heavier).
arjunior45
29-03-10, 19:10
What do you call "the very first Uno turbo"? Ive pulled many engines apart and never seen a forged piston.
The first exemplars of the Uno Turbo that came to Greece had forget pistons. I know that because I saw them.
Are you sure that's not a typo? Forged pistons are generally designed to be lighter than OE. Your comment would suggest there is only a single option (that is heavier).
:doh:
Duly edited (I think I must have posted that up while I was half asleep and would have been better using my time in bed) :tapedshut:
Thanks very much guys. Really appreciate the advice. Think I should put a good RPM cap on it then and keep things cool until the day comes to split engine and block for a rebuild - not cheap these forged pistons!
Hi, guys.
Could you please enlight me a bit about the rpm "cap"?
I'm not sure what that means, just think it should be about engine's safety limits...:tapedshut:
Thanks a lot.
Cheers,
C.
Hi, guys.
Could you please enlight me a bit about the rpm "cap"?
I'm not sure what that means, just think it should be about engine's safety limits...:tapedshut:
Thanks a lot.
Cheers,
C.
I was just refering to not going over 6500rpm, I did it by just watching the rev counter, but I guess you could fit a rev limiter if you were worried about getting carried away.nn:smile:
Difficult with OE cams as it's all over by then anyhow.
arjunior45
02-04-10, 07:11
a rev limiter is "fitted" inside the ecu {I.A.W.} and you can program just 4 hex values for the rev limits you want!!!
Cams don't matter as much as the turbo.
7200 is the limit CG put on the stock 2L engine to maintain reliability. I've stuck to that for a long time and never had a failure, even with a 20 year old engine.
With stock pistons and conrods you can see 300bhp with no problem BUT i would definitly fit a spesso head gasket,very good oil(motul v300) and wrap the manifold or ceramic coat it, so you keep the heat of it away from the head(camshaft).
The stock fuel injectors go to around 330 bhp thats the peak...tested with no problem whatsoever. But be sure you have a healthy oil pressure. We just recently find out that the stock oil gauge lies quite a bit. We measured it with a industrial mechanic gauge which is very precise.
The figures were like that(left side original one,right side industrial):
5bar -7bar
4bar -4bar
1bar -1,5bar
We checked this on two cars and both lied quite a lot.
Which mods do you have in mind?
Cheers. I already have the group N spesso head gasket - it has been in it for 6 years and I hope it lasts a good while longer as it is not cheap. I also run Silkolene Pro-S 10/60.
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.
And head bolts should be changed to 12 mm diameter if you will go for high boost. Group A spesso head gasket would be a better choise ;)
And head bolts should be changed to 12 mm diameter if you will go for high boost. Group A spesso head gasket would be a better choise ;)
Unfortunately the previous owner who fitted the gasket just before selling it to me can not remember if it was A or N. He said it definitely did not have separate fire rings so as far as I can tell that rules out the A.
http://www.nyssaracing.com/shop/spesso/SpessoRacing_05_01.pdf
Would of been good to know the thickness too. Well, if I don't run more than 1.2 bar then I should be ok....he hopes!
Do head bolts need replacing each time they are removed on the Lampredi engine? As I am not planning to split the head and block until a time that it is needed I will live with the OEM head bolts which I assume are 10mm.
Is drilling and tapping the block to 12mm something the home mechanic can do or is it best taken to the engineers? Have the tools but not the experience.
12mm head bolts are a total overkill at this level. An engineer is required for the modifications.
That's good to know. Cheers :)
If you gor for 300bhp you won't need those 12mm bolts and bigger injectors. If you go for the bigger injectors the fuel map will need to be fully adjusted(which is a lot of work :) ).
I can get you a complete map from my ex Q4 with the these mods:
-tubular manifold
-bigger IC
-siemens deka 630cc injectors
-walbro fuel pump
-ported head
-integrale manifold
-big integrale turbo(TB0385)
The car works just fine, the AFR is spot on it puts out around 330-350 bhp. With few minor adjustement it would work for your possibly future setup.
Juan AR155Q4
06-04-10, 19:15
mmmm, would you share it with all?
arjunior45
07-04-10, 10:09
yes, it will be interesting.
I think it wont be such a problem to share it :)
We would appreciate it :)
I will upload it somewhere when i get it on the computer:)
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.
I can quite happily limit it to 6500, should be quick enough by those revs with the planned parts.
Then I would spend the money on parts that really makes difference in performance - unless your budget is unlimited :)
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!!:eek:
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
08-04-10, 14:32
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?
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.
4-2-1 turbo manifold? Are you sure?
Edit: Unless you mean a twin entry turbo??
4-2-1 manifold would be for a single scroll turbo martin
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
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: 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?
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?
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
14-04-10, 12:49
You mean this one?
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
15-04-10, 09:51
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?
was ?450 for std steel and ?550 for stainless steel.
This seems like a pretty good price to me :cool:
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.
http://i3.photobucket.com/albums/y85/1NRO/turbomounting3.jpg
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.....
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
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...
Ah yes, that pesky packaging. You think you have problems, the gralies are even worse.
Juan AR155Q4
16-04-10, 13:35
If you have two pipes instead of four you will need less room no?
Well, I'm talking about the 4-2-1 design, and as shown before, it?ll depend on pipe's length. Saab cast design need less room but the tubular one needs a lot more.
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