Hey guys,

So what is your guess on max hp while staying N/A on these 3.2L engines?

With headers, dual 3" intakes, ported/polished, cat delete, 2.75" catback exhaust and a tune I can probably see around 230-240 to the wheels...

Add cams (which are super super expensive) and probably around 250...

???

(The s2000 crowd has been able to get their 4 banger to 300 hp to the wheels! And their engine is only a inline 4 2.0l!... we should be making more... what do you think is holding us back? Aftermarket support?)

 

umm V6 torque ? hehe seriously 300 hp and what kind of torque ? sub 200 in most cases ... their big advantage is they can have silly lopey cams in there since their vtec system lets them retain a decent idle with it. you just can't cam this engine that much and expect it to retain decent vac at idle or not lope like a v8 friday night drags special.

forced induction is your friend if you want ponies at a reasonable expense.

 

Engine speed (RPM) is a direct relation to horsepower. Those 4 bangers (actually 2.4 liters) scream from the factory. Something to the tune of 9,000 RPM if I remember correctly. Like Intensblu said those S2000s don't make any torque.

There is a lot of potential with these engines but as you mentioned the aftermarket is slim (but growing). All the ways you described are good examples to build more horsepower. There is another way, although expensive, to add quite a bit of ponies and that is the stroker kit.

Just imaging if there were intake manifold options, different cam shaft profiles to choose from, higher compression pistons, you know, pretty much what is available to everyone else - these cars would fly!

Oh to answer your question, the biggest claim that I have seen is from Renntech. Yours for the low low price of $14,900.

 

The intake manifold is a pretty damn good, in fact it has the longest designed runners in the industry.

I haven't had the privilege to examine the 112 cylinder head, actually porting the head and adding larger valves could easily bring up the power output to 10 hp/cylinder, maybe more if done in conjunction with bumping the CR up another point or two. You can easily get the little 3.2 L to put out 300 hp.

After that I would start looking into a big bore piston kit. I know LA-Sleeve makes high quality cast iron sleeves to any dimension you like. Here is their website: http://lasleeve.com/master.html

Actually now that I think about it, making a big bore kit would probably be an easier place to start making horsepower vs. porting and valves.

 

I wonder how much more CR the heads will allow, crank that sucker up to 14:1 and run 100-110 octane fuel. Might yield some insane power close to if not more than a stock SRT6 motor. I only wish we knew what the cylinder pressure is on the SRT6, vs stock 3.2?

I know National Instruments sells a piezo cylinder pressure sensor, but you need to order their basic software to communicate with the sensor.

 

Long runners are good for torque and that's it. The factory manifold actually has both long and short they are controlled by the ECU.

The heads should be fine provided there is enough valve clearance, the weak links would be the hardware
(head studs) and gaskets.

 

I don't see the head studs to be a weak link, since the SRT6 uses similar design head if not the same heads. the SRT6 puts out 410 hp modified, so the heads studs can easily handle the pressure.

The weak area might really be the crank NA, but who knows?

Big bore kit would be a safer upgrade, if only you can find a shop skilled enough to make a quality piston with plenty of valve relief, preferably forged alloy slug with new sleeves.

LA sleeve carries a full sleeve kit for LS1's for only $750, not bad price for speed parts, granted you do have to hone them to fit your piston.

 

I was under the impression that the only diff between the srt motor and na was pistons (lower compression) and engine management, and of coarse the blower ... I don't see why the na motor should not be able to put down 420 to the wheels stock trim. My srt-4 put down 485 whp to the wheels stock motor just fine and 530 wtrq.

 

That's provided that the limited/base models use the same hardware as the SRT. Based on experience I tend to believe the AMG built engine would use better grade hardware such as ARP for example.

Since his question was max horsepower for a normally aspirated engine the crank should be fine. If you started spraying or boosting then the crank becomes a liability.

That would be awesome if there was a reasonably priced stroker kit for us.

 

The pistons, crank, rods, cams are all unique to the SRT. I'm sure there are other items too but those are the ones that come to mind.

I have often wondered how/why some engines of similar size can make vast differences in horsepower. Is there more potential in these engines that no one has even begun to tap into?

Those are some damn good numbers on your SRT-4. What are the specs on your engine?

 

I don't think there is a chance anyone can afford to manufacture cranks to stroke the crossfire, a bigger bore is much cheaper way to make c.c's and you get to rev a little higher than a stroked motor with stock cranks.

Don't get me wrong I would totally jump on a stroker crank if they where offered here in the states for $2,000, but a $10,000 crank just doesn't do it for me.

 

True I bet just because no one has really tried to push the limits of either motor srt6 or limited I bet we would be surprised how much they will handle... the srt4 has the agp50trim, safc, 750cc injectors, agp fmic,and all supporting mods. As far as motor all stock...cams, head everything even stock clutch...starting to slip now though with 63,000 miles ... I really don't think we would have problems in the limited on power even if it only can handle 400 that is still mid to low 12's in the quarter, and still be able to go pull 1.2g's in the lateral. Can't do that in the srt-4.

 

urh, urh urh!!, check this out Mercedes has already took the 3.2 m112 and bored it out, thus creating a 3.7 Liter pretty damn cool!!!
Look at where the Torque numbers are at, 3,000 - 4,500 rpm, man is that sweet!

http://en.wikipedia.org/wiki/Mercedes-Benz_M112_engine

The E37 is a 3.7 L (3724 cc) version. It retains the 84 mm stroke of the E320 but is bored to 96.8 mm. Output is 235 hp ECE (173 kW) to 245 ECE (180 kW) at 5,750 rpm with 254 ft. lbf (344 Nm) of torque at 3,000 - 4,500 rpm.

Start scrounging for wrecked ML320's that motor could easily make 300 bhp without a sweat, otherwise Bore and sleeve a m112 block and order ML320 pistons. MBZ also has an AWD version, though I doubt any of it could fit under a crossfire's chassis. Would wild to have an AWD Crossfire, lol.

 

Now you making me think.
hummm... what if...

 

SHHHhhhooosh... please let's not advertise this little factoid too much.

 

If I were to do a n/a 3.2, I would just forget it is a Mercedes and do it like we did Chevy's and Ford's before there where stroker kits and such. I would build a mystery motor. looks normal on the outside, who know how big it is in the inside. I would max the bore and stroke. The crank would be offset ground, find rods and pistons that could be used. balance the whole assembly. You would need larger cams to support the displacement, and I would port and polish the heads and extrude hone the intake. How big can you go?

Well we know that some tuners are selling 6.1L 24 valve V8's and the three valve V8 is the same basic engine as the V6. This would equate to a 4.6L V6. If you wanted to keep it more simple get six rods, pistons and rings from a 5.5L bore the block, offset grind the crank, balance the assembly and you have a 4.1 Litre V6. I would call one of the many US cam manufacturers and have the stock cams re-ground. Isky would probably be willing to do this. You would probably need bigger injectors like maybe SRT 6 injectors.

If you wanted to play around like this you can get a 320 engine for a little as $300 - $600 on Craig's list. Usually an ML320 engine. Maybe you can also find a blown ML55 engine that still have six good rods and pistons? One key to not getting robbed is to stay away from people who work on Mercedes and find the reasonable guys working on american engines. It doesn't matter that the engine is Mercedes. the principles are all the same.

I just checked some bore and stroke number and the 3.7 is a 3.2 with stock stroke but with pistons and rods from a 5.0 V8 I'll bet this is how Startech makes their 3.8

 

Cams for ml series are cheap, I wonder if they have a different grind on them compared to our crossfire.
http://www.oempartsdirect.com/

I ordered an intake and exhaust valve, just to have for specs and curiosity. The ML320 piston is about $250 each, I would like to get a stock 3.2 piston for comparison. I think I'll try and source an entire ML320 engine before I commit to buying one piston. Damn they also want $100 for one ML320 injector. I’m gonna have to do some calling around. Can't wait for my neighbor to get his injector flow test machine up and running, then we can find out if there are any differences in injectors.

 

Hm a stroker would be way to complicated I would think and costly.

Keeping costs down, without stroking it what else could be done? (it is already a 3.2l engine guys (like I said guys in the s2000 crowd have a 2.0l and thats not holding them back).

So keeping the stock displacement, what else? Raising the stock compression with a thinner head gasket, and water/meth injection I think would help... Anything else?

I will be making a custom exhaust and intake, what do you think the best diameters are for them? (I think a single 3" intake and single 2.5" exhaust would be the best) What do you think?

 

you're not seeing the entire picture with the s2k guys ... they have ability to alter their cam profile at high rpm ... you cannot do this with the 3.2 therefore if you put a nasty cam in there that will give you a awesome high end boost your idle will suffer with lopeyness and reduced drivability ... often times making the car useless as a daily driver.

they are making their horsepower cause they can have the crazy lift required to do so ... we cannot ... so the options are increase displacement so you can run a nastier cam without it affecting drivability or go forced induction cause it makes MUCH more sense in this case.

 

Also they have about 3,000 rpms more of usable power. If we redlined at 9K we'd be making crazy power.