More power from 2ltr 8 valve engine.

All technical questions and answers regarding starions, being modifications to maintenance.
T-man
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More power from 2ltr 8 valve engine.

Post by T-man »

Ok I've given up on my DOHC dream and bought and installed a 2.0ltr 8 valve engine. What's the best way to extract more power from this power unit? I know about the air box mod and the better exhaust flow which have already been done. Here's the guide lines, I would like to keep the ecu and keep it as simple and straight forward as possible. Oh and I've not got bottomless pockets or an of shore account!

Thanks in advance,
T
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Alspos
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Post by Alspos »

1. Intercooler

2. Raise boost.

That's about it.
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Post by JayME »

I've been a bit of a keyboard warrior on this subject recently as I'm starting to mod mine (Beginning with a TD05 turb). Lots of info on here but its fairly scattered. Stock ECU/Fueling/Ignition control is a fairly limiting factor. But if you have bottomless pockets you can pay someone to setup MPI and tune it? :p

Exhaust
Make it bigger, restriction is bad. <250rwhp 2.5" will suffice, >300rwhp 3" (+) seems to be the consensus from info I could find.
Here's a good article that was linked on here elsewhere: http://www.tercelreference.com/tercel_i ... heory.html

Intake
Again remove restriction - The problem being that the biggest one is the Air Flow Meter. Really the only way to do away with this is an ecu change. . . There are people on here who have removed it with the standard Ecu (The theory being they run a factory map sensor anyway). I'm a little unsure about this.
Intercool - size appropriately to your supporting mods. To big can introduce lag and make the car less responsive, too small introduces restriction and you make less power.

Turbo
Plenty of newer more efficient ones around. Again important to size appropriately to supporting mods/desired outcome. Lots of people have a lot of opinions on the subject. There are a few people suggesting the TD05 16G seems to be a good match to a mildly modified Starion and require relatively little modification to fit (Needs to be Evo 1- 3) but the skies the limit if you want to do custom bits. As Alspos mentioned you can get away with a couple more lb's boost if its intercooled.
Here's a guide to fitting a TD05 someone on here made:
http://starion.mrbdesign.com.au/EVOIII.html


Engine Bottom End
Factory Starion engine is quite low compression. The suggestion is if you rebuild to go Dohc pistons which raises the compression a bit which surely means more power . . . .
Reference: http://forums.austarion.com/viewtopic.php?t=15357

Head
Apparently a performance cam will really 'wake a Starion up'. I cant find my reference for this but know of people who have done it on relatively stock Starions (factory ecu). I was also intrigued by the thought of fitting a 4g64 head. Supposedly bigger valves, so more flow and bolt straight up?
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Post by T-man »

Thanks for the quick responses guy!
Ok say if I was to use the DOHC pistons I have and use the evo 3 turbo, can I still use the standard ecu? And will the performance difference be worth the extra graft?
Will I be getting enough bang for my buck? Or am I better selling the parts I have and spending the money on something that will get me better results?

Thanks,
T
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Post by popup »

The problem with the factory ECU setup is finding information about it! If you require more performance with modifications made to the engine, then the map will need to be tweaked. You could try a piggyback route as I think they often do that to the 2.6s in USA but I think you'll only get fueling changes from that.

Factory pistons are reportedly only good for about 12-14pis of boost and I think even that is pushing it.

Get the engine installed as it is, give it a service, check compression and adjust valves etc. Install a proper MBC with the ball and spring as that can help get the turbo spooling quickly and earlier in the rev range.

Then figure out what kind of engine you want, more boost, more power off boost. Higher revving engine, or torquey?
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Post by thrash »

going mpi is a matter of reliability and drivability, not necessarily power.

changing out the ecu without doing mpi will just allow you to control larger injectors - one factor to your peak power ceiling, but may not necessarily give you any additional reliability.

If you swap out the ecu and go mpi, you get more reliability. You might get some additional power by tuning the fuel and ignition better, but this *should* only really be the case if the original ecu wasn't working right.

Think about a carby vs efi. There are still carby fed muscle cars around making 900hp at the wheels and what not. Switch the same car over to efi, and you won't make any more power - the carby is tuned to the engine's full potential already. However, the trade off with the carby is that part throttle low rpm street driving and idling suffer due to the size of the carby etc. Modern efi more or less eliminates this trade off by giving you more control over your air fuel ratio at all rpm. Peak power remains unchanged.

consider tbi to be about half way between a carby and efi. You get electronic control of the afr of the engine as a whole, but you cannot specify the afr of each cylinder. As long as everything is working right, peak power will not change. However, if at higher power levels, say cylinder 4 is leaning out while the rest are fine, you have no way to correct this except to throw more fuel at the entire engine, which will then reduce power and fuel economy.
Last edited by thrash on Tue Aug 26, 2014 12:54 pm, edited 1 time in total.
quest wrote:
WANTSOM wrote:Personally, I find sloppy boxes very unsatisfying. I like them tight and taught to the point that if you dont have to push to get it in then its probably too old and time to get a new one :P
don't try explaining that to her tho..... just leave. lol
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thrash
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Post by thrash »

question is, what are your goals?

do you want a little bit more power and a lot of reliability?

do you want a lot more power and a lot of reliability?

do you want more power and are ok with not so good reliability because it's only a weekend car?

Talk to tomsun or John196701 on this forum. They both have high powered sohc cars. They can tell you a lot about their journey and what they feel would be worth your while. tomsun recently reached the 200rwkw mark, but he's done a lot of work to hsi over the years. john's has a lot of custom fabrication done, so his may be a bit more out of your reach, but at least they have the experience to steer you in the right direction.

My advice: do it in bits and pieces. boost gauge first. Stock boost should be 7psi, but your boost gauge may read differently (they are not always calibrated correctly). Just remember what it says as a baseline.

Then get an intercooler and a boost controller - one of the turbosmart manual boost tees won't cost you a lot, and will do the job. A second hand galant vr4 or early evo intercooler should do the trick, and might be easy to find in your neck of the woods. Old saab intercoolers are quite sizable as well. Whatever you can get your hands on cheaply that will fit for now. Truck intercoolers will be too big at this stage, so steer clear of them. Going too big will hurt your throttle response and not give you anything in return.

Wind up the boost 1psi, then drive around and listen for knock. rinse and repeat until you're happy with the power, or it starts knocking (in which case stop driving immediately and wind the boost down 2psi from there), or it hits boost cut (wind boost down 1psi).

If you're happy with the extra power this gives, then you might as well stop here (for now ;)).

if you want more, next step would be a better flowing exhaust. 2.5inch at least, but some expert exhaust shops have told me that 3 inch actually offers less drone and is a nicer exhaust noise to live with.

With the new exhaust, test drive very carefully. check that your boost level is the same before and after the exhaust. If it isn't, adjust accordingly while still checking for knock.

If you still want more power after this, you could go a larger turbo such as a td05h-16g, which i believe will fit with some modification (i'm sure the more knowledgeable folk on here will correct me if i'm mistaken :)), but if you do this, wind the boost back down to stock and start again, as your tbi may not be able to cope with the larger amount of oxygen from the bigger turbo at the boost level you have been running.

One thing people haven't mentioned is cam upgrade. After the turbo, if your fuel system is coping and you still want more, I would say a cam upgrade is next. The cam seems to be the limiting factor when it comes to achievable peak power with the sohc head. I suspect, however, that by this stage, your injectors will be well past their limit, and if you want reliability, I would highly recommend saving up before your turbo upgrade and doing mpi, turbo and cam together, as it means you only have to get the ecu tuned once and save there, despite the longer wait.
quest wrote:
WANTSOM wrote:Personally, I find sloppy boxes very unsatisfying. I like them tight and taught to the point that if you dont have to push to get it in then its probably too old and time to get a new one :P
don't try explaining that to her tho..... just leave. lol
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Post by Alspos »

As you mentioned....mods need to be cheap and attainable. While going multipoint and aftermarket ecu will do all the things mentioned above, they are not cheap. Head swap, bigger turbo, forged internals = more money.

Look on the US forums or ebay for a complete stock intercooler setup. I am not sure what model your car is and what injection setup it has, but you can adapt stock stuff to suit. And the stuff should be cheap (postage to Scotland may kill a bit though.)

Or....Buy a different cooler that will fit (ebay, local supplier etc.) You will have to make yourself or get made all your intercooler pipes to suit and will have to buy clamps and silicone joiners etc.

Once it's cooled...then you can up the boost a bit with a boost bleed valve or MBC as mentioned earlier. Unsure if the Euro model has a boost cut like the Aus model, but you will know it when you hit it. Set it around 10-12psi, above the 7psi stock and below the cut threshold.

For added fun factor if you don't already have one, get an LSD.

I have done all the above in one form or another, my car/s is fun and fairly reliable, and I haven't had any complaints from the Minister of War and Finance about the size of any financial outgoings. It's not stupidly quick or scary, but it is better than stock.

Just my 2 cents worth.
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Post by JayME »

wow that got wordy :P

Although I don't fundamentally agree with everything that's been posted the key points are there. Work out what you want, start with the easy stuff and there are other sohc examples on here which provide a bit of a recipe - Do your research.
Ok say if I was to use the DOHC pistons I have and use the evo 3 turbo, can I still use the standard ecu? And will the performance difference be worth the extra graft?
Will I be getting enough bang for my buck? Or am I better selling the parts I have and spending the money on something that will get me better results?
I cant see why Dohc pistons couldn't work with factory ECU/fueling but wouldn't think this would be bang for buck

My reason for going a TD05 first off is I have a hybrid TC05/06 that runs out of puff by about 5500rpm. Not that I thrash the car that much these days but I'm ultimately hoping for a wider range of useable power - its probably going to be a more laggy . . . .but again its all part of a larger plan broken into (semi)affordable chunks.
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Post by fugazi »

Yes to all above, but...
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Post by Neil »

^^ what he said
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cheap power

Post by 4gpwr »

I think I got about 180 rwk on a stock ecu at 18 or 20 psi , in my starion , it took a lot of dyno time , it had a intercooler ,re - graphed dizzy , a rising rate fuel pressure reg , 3inch exh with a big dump pipe , and a high flow turbo , also had a fuel cut defender of sorts , the set up was a time bomb , it did a few head gaskets , cracked a few pistons , and also cracked one of the main caps on the block , the only reason I did end up going mpi at that time , is something stuffed up electronically and I didn't have access to parts
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Post by WidebodyWoody »

I am selling my stock intercooler and piping around End of October start of November if you haven't found one by then. :beer
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Post by T-man »

Wow now there's a lot of info! The car in question is a 2.0ltr wide body with intercooler and LSD as standard.
The way people are coming across is there is very limited power to be had with the standard ecu.
So more power would mean more money. Yes I would like more power but at what expense. Here's my take on it. I will get the exhaust custom made to 2.5" then a bleed valve of some sort and adjust accordingly then a rising rate fuel pressure regulator.
That would basicly be the max I could go with out spending stupendous amout of cash.
If I was to spend stupendous amount of cash where does it end?
With the quest of getting more power costing $$$$$$$ would I not be better getting another car which would be easier to tune for more power? But then what would I buy that has the starion presence?

T
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Post by Alspos »

T-man wrote:...... and adjust accordingly then a rising rate fuel pressure regulator.
Personally I would stay away from this, it's a cheats way and unpredictable without being able to program the stock ecu to suit.
If I was to spend stupendous amount of cash where does it end?
When your pockets are dry. :)
With the quest of getting more power costing $$$$$$$ would I not be better getting another car which would be easier to tune for more power? But then what would I buy that has the starion presence?
That's the conundrum, if you add up the amount of money some people have spent on their cars, they could have bought M3's, Porsches, LS1 powered whatevers etc. But that's not the point is it. :wink:
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