Evo Engine / Tuning

[Gorilla]

Hi,

I am trying to obtain some realistic ''base''
figures for a Evo engine performance based on
the following specification-

97.3 Bore
12.1 C/R
Head -Ported Exhaust and Polished- Intake cleaned up
AMG P/P Cams
Uprated Valve springs/ Ti Retainers
Revert to single Cam Chain
Delete the power steering pump
50mm ITB's [ Slides loose to much mid Torque on a Road Car]
Large Bore Header/DTM style
Twin 55mm dual exhaust
De- Cat
EFI/ Stand alone ECU

Would an Evo Engine built to this specification
make somewhere around the 280/290 BHP
level ?

Or is that being over optimistic ?

Does anybody have a similar specification
engine that is willing to disclose their
power figures please ?

Many thanks,

Regards,

The Gorilla.

[Rouven036]

Hi Gorilla, i would recommend to keep the throttle body diameter under 50mm i.e. 48mm or 49mm (big diameters will lower your torque in low and mid rpm range, there a higher air velocity is needed to get the cylinders properly charged and this could only be maintained with not to big intake runner diameters, smaller dia.=higher air velocity, big dia.= low velocity), also a headder in dtm style won't give you the expected result if not choosen carefully. there are two dtm exhaust manifold versions, one was 4 in 1 style (higher power output in a very high rpm range, but low midrange torqe- not recommended for street use) and the 4 in 2 in 1 version (higher torque and power in lower rpm ranges). i think you are able to reach your target even with a standard 2,5 exhaust manifold since it has a bigger diameter as the 2,3 version. a upgraded exhaust with 100cpi cats (if any) should be used anyhow.
a power output of 280hp is realistic and nothing what needs a rocket scientist, it is very important to get the aftermarket ecu properly tuned on the dyno, that will give you the best results....

[Gorilla]

Hi,

Rouven036- many thanks for the response
and the information.

It seems that the Power and Torque characteristics
are very similar to the BMW S14 4 pot.
The BMW 4-2-1 [Known as the Rally Header] due to its
better mid range Torque, is a little better
and suited to a Road car engine.

Same again on the Cam lift, higher lift cams
may make more BHP but it will be at the
higher end of the rev band, which is not good
for a road engine that is not making lots
of Torque.

On most of the Intakes I have seen on the Evo
engine's there is not much length to the ''runners''
due in part to the engine angle and the front strut
housing. [distance between the intake face and housing]


On your point about a greater air volume not having
velocity due to overall diameter then Obtaining
longer runners by some means to induce
a Ram air effect at the Throttle butterfly
or slide face , I would have thought would assist in
increasing air velocity in the intake.

On the S14 engine BMW have various length
runners for their Carbon Inakes as a means to
extract a little more Torque or Power, which
ever was required.
Having the throttle butterflys as close to the inlet
as possible would also assist with throttle response.

I understand that its not Rocket science in making
more power from short stroke oversquare twin cam
16v four pots, but understanding what has been done
before and any major black holes that may have
developed sure helps.

Many thanks again for your response and good advice.

Regards,

The Gorilla.

[Rouven036]

You are welcome...As said the runner length and dia. is very important for the torque curve and drivability of the engine on road.
attache you can see a picture of my engine, also it is not what you prefer (slide system), but you can see that long runners are possible in a slightly curved layout this for sure could be done similar on a itb system...


best regrads

[Gorilla]

Hi,

Rouven036- seems that runner length
is a topic on most 16v Forums.

http://board.s14power.com/showthread.php?t=6484

Not going to go to those lengths !!!!!!! no pun intended.

Regards,

The Gorilla.

[Gorilla]

Hi,

Rovven036- what compression pistons are
your running in your Evo engine please if
you do not mind ?

I was looking at your Dyno figures on the 190 rev
and was juts trying to work out your engine
spec with the slides etc.

Many thanks,

Gorilla.

[Rouven036]

Hi Gorilla, uff i totally forgot my rev account...
anyhow the internals of my engine are bone stock, means, cams, pistons (cr 9,7:1) etc. all untouched.
I don't know which diagramm i put on the rev. board, have to check that old thread again. there is one where i entered the stock figures for comaprison. the gains in torque and hp are pretty obvious, on the other side you can easily point out that the torque curve between 3000 and 5000rpm has a lot off space for improvement (nevertheless there is much more torque than stock...).
over the time i collected a lot of dyno graphs off different set ups as itb+cams, efi+stock intake with or without cams etc etc etc and it is always the same, that you'll loose more or less toque in the midrange. to keep the torque loss in midrange as low as possible, the solution for me will be the use off an evo2 or only slightly more agressiv intake cam, the slide system due to its runner lenght and 8 injectors, a evo1 dtm head with 39mm intake valves, a 4-2-1 plus x-pipe with 2 seprerate 100cpi cats connected to an amg pp exhaust system and pistons with a compession ratio off 11,5 to max. 12,0....hopefully this will get me some 280+hp with sufficient torque in a wide rev band...

best regards

Rouven