getting more out of a 2.1L n/a

[ludichris001]

Hello

as you may or may not know, my '89 EMS notchback known as "Mia" has a 2.1L in her - the original engine gave up on the way home from buying it (engine was already shot, i purposely finished it off ) i then went to a T8 i had from a previous C900, which also required an auto to manual conversion. got sick of that, and fitted the 2.1L from the written off parts car i also got with the EMS

anyway, i had the 2.1L engine and box in within a weekend, ready to take to trade school the following monday for our dynamometer course.
first result was 88Kw at the wheels, even with a vacuum leak caused by a broken O ring/pintle cap on #1 injector. from a 2.1L n/a i was quite impressed as were the other members in my group. i was mainly impressed because it had more power and torque then the previous T8 engine.

That was 2 years ago, and since then i have been trying all sorts of different things to get some more power ranging from varying the length of the intake pipe (between TB and AMM), "pod" air filter, fuel injectors, ECU's etc etc etc, and using my "butt dyno" to measure changes in performance

currently i am using a DI system from a 2.3L n/a 9000, with the original LH2.4.2 ECU (bosch -944) for the 2.1L. have new fuel injectors and a 2.25" exhaust, which is press bent...

Butt dyno results showing a little increase in performance (it "feels" like its pulling harder, especially once i pass the 4500RPM mark)

so far i have found that the shortest intake pipe provides the most torque over the standard pipe (proven on dyno), the pod filter along with the deflector plate from a T16 helps more cool air get into the intake. (deflector plate is the metal piece attached to the radiator support which directs air into the stock intercooler) and removing the meshes from the AMM has just about no improvement (i actually lost power with the meshes out)

now moving on, i am currently focusing on the exhaust side and wish to iron out all of its imperfections, firstly by throwing out the 2.25" press bent system with a generic chambered muffler (it does sound good but i am beginning to think its been quite restrictive)

so... i am looking for some more top end torque, and from what research i have done, bigger is not always better in the n/a world. i want to be able to have the least amount of restriction as well as keep exhaust gas velocity high enough to keep/improve the scavenging effect the exhaust has. for starters, i will be making my new system out of mandrel bends, and using a straight-through muffler.

i was considering cherry bombs but nobody around here stocks them and the cost to ship them from the US is more than the cost of the muffler
but i am still looking into other muffler options. unless someone can convince me that the extra $$ for the cherry bombs is worth it...

this is the main concern i have, and the reason i have made this thread - exhaust size.
stock sizes range from 1 7/8" to 2 1/4" depending on year/model variant/induction type.. as we all know saabs weren't meant to be "loud"

i am stuck between going 2 1/4" mandrel or 2.5" mandrel from the header pipe back, so i am after some opinions/experiences/any input anybody has to offer.

eventually i will be turning this into another project once my turbo 900i is back up and running. as far as the 2.1L goes, it will be staying n/a. my eventual power goal is around the 200kW mark with a peak RPM between 7200 and 9000. Yes it seems a bit optimistic, but i see it as a worthy challenge.

Any input (besides "chuck a turbo on it") will be greatly appreciated

Chris

[euromobile900]

Have you thought about upping the compression? I'd throw on a head from either a 2.0 for more compression, or an '85 t16, for the most compression. See how DI takes care of it, and adjust fuel grade accordingly.

What about switching engine management to T5? LH 2.4.2 is good for now for fuel, but not very tunable for when you want to raise the rev limit. They made N/A cars with T5.

I'm sorry I know nothing about exhaust. I've heard that the stock 900 Turbo system is fairly non-restrictive, and it's fairly cheap, but you sound like you want bigger.

[ludichris001]

i have a T5 head waiting to be ported, shaved and fitted , i am going to save that for when i take the car off the road for resto. Megasquirt is also being thrown in the mix.

but for now i am focusing on the easier "bolt on" mods - mainly the exhaust

[Turbofrenzy]

In basic terms tuning all petrol engines is the same, get the maximum mixture in, burn it efficiently and get it out again. Yes there are differences between all types of engine (n/a, turbo, supercharged, nitros) and indeed it depends how efficient any given engine was to start with.

So as you know, unrestricted intake, ported head, big valves, cams, valve springs, solid lifters, compression ratio, lightened and balanced engine internals, fuel quality, exhaust manifold and system, ignition system, fuel system.
How big is your budget? A 9000rpm rev limit is expensive

On an n/a I think a 2.5 inch exhaust is max.

[ejenner]

Will want upgraded valve springs or solid lifters in that new head if you want to get to your raised rev limit.

Could get a 2.3 crank and rods in there as well. Need to shave some material off the counterweights on 2.3 crank to get it to clear the gearbox. Its been done so is possible. The 2.3 crank with the 2.1 pistons is going to make it about a 2.4L - Will still be oversquare so won't lose too much top end to low down torque.

[Turbofrenzy]

Originally Posted by ejenner

Will want upgraded valve springs or solid lifters in that new head if you want to get to your raised rev limit.

Hmmmmmmm just said that 1 post previous

Originally Posted by ejenner

Could get a 2.3 crank and rods in there as well. Need to shave some material off the counterweights on 2.3 crank to get it to clear the gearbox. Its been done so is possible. The 2.3 crank with the 2.1 pistons is going to make it about a 2.4L - Will still be oversquare so won't lose too much top end to low down torque.

Who's done it succesfully? Several have tried, but I thought they'd all given up!

[ejenner]

I wrote mine at the same time. That's how it happens when two people say the same thing. Was doing some other bits (like a phone call or something) then hit 'submit'

With the 2.3 crank in the 2.0 engine I think the one I saw which was working as far as I remember was an American one which was done by someone who does not post that much and just came on the forum to share what he had done rather than to ask questions. I think he had actually completed it.

I would like to do something similar with my 2.1 block. I will probably try and get as far as possible without actually spending mega bucks on engine work. I think I could sensibly get away with just big and little ends and crank journals. Leave the cylinders as they were. Wack it all in and hope for the best.

[ludichris001]

Originally Posted by ejenner

Will want upgraded valve springs or solid lifters in that new head if you want to get to your raised rev limit.

Could get a 2.3 crank and rods in there as well. Need to shave some material off the counterweights on 2.3 crank to get it to clear the gearbox. Its been done so is possible. The 2.3 crank with the 2.1 pistons is going to make it about a 2.4L - Will still be oversquare so won't lose too much top end to low down torque.

yes valvetrain is one of the other things i will be looking into, when i get the chance i am going to look into some toyota engines, which have the adjusting shim in the top of the bucket, just hoping i can find ones the same size. it will make adjusting valve clearances a whole lot easier as the cams will not need to be removed to replace the shims

stroking is one thing i will be staying away from, mainly because i want to keep the same engine capacity (2.1L) and see how much i can actually get out of it.

the 2.1 in my EMS is what i refer to as a "freak engine". Meaning that it just wont die! i have tried to kill it (to give me an excuse for a rebuild) and it just keeps going.. i ring the absolute crap out of it on a daily basis and have never seen blue smoke out the exhaust, never heard a single rattle or knock or any abnormal noise, ever! i did a compression test a couple of weeks ago and still have 175psi on 1, 2, & 4, and 165psi on number 3. At close to 300,000kms i am very suprised at how well this engine is still running, i have noticed a slight drop in performance, but considering the way i drive it, it is expected.

The exhaust is the main thing i am focusing on at the moment as it is the easiest thing to do to free up some more power, without touching the engine itself. press bent pipes usually shrink about 1/2" at the bends, so theoretically the 2.25" exhaust i have is no better than a stock one, just louder.
with some higher flowing mufflers and mandrel bends i am really hoping i get the result i want. only thing that sucks is that nowhere in australia stocks cherry bombs, which from what i have researched, are quite good at what they do.

[sonett1]

'Butt dyno' tests are pretty useless, its very difficult to feel a 10 or even 20bhp increase, a better way is to use the same stretch of road with markers and time your runs, of course its even better to take it to the same dyno each time you carry out a mod, but it can become expensive. Its usually the increase in noise what fools you into thinking you have more power.

Be prepared to be dissapointed with your exhaust modification, for your engine 2.25'' is about right, changing the exhaust manifold will yield more.

The 2.3 crank modification is quite straightforward, Ejenner has only told you half the story, it's not just a case of turning back the crank webs.

[borderwave2]

How do you like having T5 on an NA car? I heard you can get really good gas mileage running it on a non-turbo motor.

needs more DI....

[B202NUT]

Originally Posted by borderwave2

How do you like having T5 on an NA car? I heard you can get really good gas mileage running it on a non-turbo motor.

needs more DI....

alot better mileage than the gal in the picy gets with the panty hose shorts on (oh please tell me thats a gal with those leatard shorts)

[borderwave2]

haha afraid not, my dad had just gotten home from a bike ride and decided not to change clothes just to wash his car.

[ludichris001]

Sorry for the late reply guys

anyway, yeah butt dyno is quite pointless, i dont really want to pay the $150 for a single run on a chassis dyno every time i change something.

and the systems in the car are LH2.4.2 and DI, not T5. i do however plan on going down the megasquirt path with this car in the future

on another note, my lovely car decided to crack the collector pipe a couple of days ago. i just bought a beater 9000CD (bought it back off my brother, who has killed it) for $300. which gives me a chance to give the EMS a rest, and more time to do the whole exhaust from cylinder head to tailpipe - more to the point, tuned length extractors

that is... after i have replaced the head on our '92 900i...

[ejenner]

The best way to get the best fuel economy from any given engine is not to fit a system designed to work with a CAT. The CAT wants 14.7:1 AFR but engines don't need that much fuel on a cruise so you can run leaner without a CAT and a fuel system which can be tuned to a different AFR target. I'm pretty sure T5 can be setup to run a leaner mixture but you are getting into the realms of some serious fiddling by that stage. Plenty of people who would call that easy no doubt.

[borderwave2]

How does one go about setting up DI with the LH 2.4.2 system?

[ludichris001]

these are the only connections between LH2.4.2 ECU and the DI ECU:
RPM signal
knock/preignition enrichment
load signal
TPS (i think)

i used a system from a 2.3L n/a (not a DI/APC)

i must admit i got sick of playing around with the DI system fitted and went back to basics (bosch EZK)
With DI:
you may notice some backfiring
it takes longer to start
the engine tends to run hotter
and it is a little laggy under 4500RPM - i noticed straight away that the engine now pulls harder below 4500 than what it did with DI and it doesnt just "take off" after that RPM mark it just keeps pulling till redline.

if DI were Programmable i would have kept it. only issue i see is that the system is tuned for a 2.3L and going by the issues i was having, the timing was too far advanced for a 2.1L.
if you still want to do the conversion then say so but i dont see it being worth the time. Programmable is the way to go.

the whole DI thing with me was just an experiment. yes it has its good points but after having it for so long i have become sick of it, due to the lack of being able to program it.

[supremedalek]

I honestly thought DI was programmable.

[ejenner]

You wouldn't bother converting to standalone DI these days. That was a conversion more popular in the days when nobody had considered retrofitting trionic 5. People also did megasquirt or other standalone ECU's then as well. I still have a standalone ECU on one of my project cars. Hence I know well how economical you can make an engine with the right tuning.