1986 conquest tsi

[torquebird]

I am new to the forum and new to this type of vehicle. i have 1986 conquest tsi with 65000 original miles i have gone over the car i changed the oil trans and rear end fluid it has a new fuel filter i need to check the one in the tank car runs pretty good i have put a 2.5 inch down pipe and 2.5 exhaust all the way out with a performance muffler. what mild mods can i make to this car and keep it reliable i am not looking to build a race car but like everyone else i would like some more performance thanks for any help you can give me

[patra_is_here]

how much do you want to spend?

[torquebird]

maybe a few grand or should i save up and put the twin cam motor in it??? but for now is 75hp-100hp extra hp somehting a stock motor can handle?

[patra_is_here]

stock block can handle about that much more.

 

i would say check the motor mod forum first to get an idea.

[Shelby]

first thing to do is upgrade the exh,,

[patra_is_here]

so it sounds like you're going for the near 300HP range. if you check the modded forum, you'll see the "300whp club"

 

some of those guys are still running throttle body (most are multiport though)

 

but, since you're shooting for 275 - 300hp, its possible on a stock well maintained block.

 

 

 

i would say the most direct and affordable way to reach 250WHP (275 and up requires more work, so i think thats out of your range)

 

would be running a larger turbo with high boost capabilities.

using a GM MAF-T to allow for tuning

using a WB o2 sensor on a dyno

using a smooth flow, proper diameter intake piping

a turbo back exhaust system

MAP sensor Diode Mod (its in the FAQ)

and then, running some sort of extra injector system, or, possible running larger injectors and figure out how to tune them to allow the car to still idle and run at part throttle without going completely rich.

 

if you want to spend more money on labor, then i would say portmatch and polish the head, port the header or buy a high flow header, port the throttle body. but from the sounds of things, you dont want to disassemble the block or head

Edited August 13, 2008 by patra_is_here

[torquebird]

i just added the exhaust and went for a ride wow what a difference i did notice it started to break up a littl bit at about 5000rpm the former owner said he had the injectors cleaned and flowed and i beleive him as they look like they have been serviced... although the person who put it back together installed the tps wrong and it was reading 5 volts all the time i fixed that before the exhaust and that helped the idle and drivabiltiy greatly. it has a new fuel filter i will check the one intank and will install an msd coil and better cables and check the plugs anything i am missing???

[torquebird]

i think 275 hp would be good my main concern was tbi system i'll look at the other forums and see what people are doing. how about a bigger intake pump and boost controlled fuel regulator to up the psi as boost increases has any one done that?

[patra_is_here]

well the stock turbo drops off around 5K i think.

 

 

you could definitely just run a larger turbo, maybe a ball bearing turbo, and up the boost and run a rising rate fuel pressure regulator, and the Diode Mod (to avoid fuel cut), but really, your bottle neck is ultimately the throttle body injection.

 

so you can keep it and be stuck at a certain limit, or you can just go all the way with multiport and standalone management,

[torquebird]

how much would we be talking for stand alone and multport i know this is the best way what is the redline on the tbi 1986 engine i dont want to damage it i thought four cllinders liked rpm but if t makes max power right at 5000 then the car is working fine

[patra_is_here]

how much would we be talking for stand alone and multport i know this is the best way what is the redline on the tbi 1986 engine i dont want to damage it i thought four cllinders liked rpm but if t makes max power right at 5000 then the car is working fine

 

well the stock TURBO runs out of juice at around 5K, and the stock camshaft timing is a midrange cam. a bigger turbo will make more power higher in the RPM range, and you could run a better cam.

 

redline is 6K for the block and head in stock form. if you run hi pressure valve springs you could go to 6500 rpms i've heard (not sure though)

 

a full multiport, with standalone, and exhaust and intake piping to suit, and having someone tune it could run you $5000+ easily. it's obviously less money if you are capable of doing the work yourself.

 

myself, doing all the work, getting parts at cost, getting free fabrication and tuning it myself on a rented dyno, could probably build one using off the shelf parts + a few custom items for around 2000. but that would be a bare bones system using a DIY ecu like megasquirt or one of the inexpensive standalones like SDS, or using used parts that members here are selling.

 

 

4 cylinders aren't any more rev happy than any other engine, the reason people think 4 bangers can rev is because most 4 cyl engines have a short stroke, and thats what allows for a higher redline.

 

if you don't know about some of these basic engine principles, i advise that you either read a few books on engine performance, or be prepared to shell out plenty of cash to someone who knows the stuff.

[mikec]

Multi-valve 4 cylinder engines like RPM. They have shorter piston strokes/larger bores to get the displacement. The StarQuest 2.6 engine has a longer stroke than most high-rev 4-cyl engines so it's not so rev-happy. Instead it makes low RPM torque. The redline is 6300 RPM but a stock StarQuest looses power above 5500 RPM and it's pointless to rev much past 5000 RPM. What causes the power loss above 5500:

* restrictive intake - the throttle body setup is just too small to feed a 2.6 engine's air appetite at high RPMs.

* restrictive exhaust - ditto. Which is why folks recommend a bigger exhaust first. Backpressure is a turbo's enemy.

* restrictive exhaust manifold & turbo: the factory TD05-12a turbo is great at making low RPM boost; it's what makes a StarQuest feel like it has a large, torquey motor. But it too ends up being overwhelmed when the RPMs get way up there... it just can flow enough air through the compressor side, and the turbine side is starts blocking the exhaust flow.

* The 2-valve cyl head limits airflow too. Oversized valves (1mm bigger) are available but don't buy a whole lot of HP for their cost. Save that mod for later.

 

One "bolt on" upgrade is to have your turbo rebuilt with a different compressor wheel: that'll make it flow more air (so it keeps up with high engine RPMs better) with some sacrifice in low RPM performance (i.e. it'll lag a little more). A common upgrade is to the 16g wheels. The compressor housing (silver part of the turbo) has to be machined to make room for the new wheel... or you can just buy a TD05-16g new. Don't grab a turbo from the "1G" cars (Eclipse/Laser/Talons) that say "16G turbo" because the rest of the turbo doesn't line up with the StarQuest installation. You can mix/match the parts and adapt it... but it's not worth the effort when you can buy the right setup (or have your turbo rebuilt to a 16g setup) for less cost & time.

 

Adding a manual boost controller to add boost pressure will add HP fairly easily. HOWEVER... it's also an easy way to blow up an engine. You MUST monitor your fuel system to make sure the engine gets enough fuel to match all the extra air you're shoving into it. An air/fuel guage is an absolute minimum... tied into the stock oxygen sensor. That won't tell you if you're nearing the limit - it says "good" or "bad" but it doesn't warn you before you get to the badness cliff. A true "wideband air/fuel" guage is the right way to go... and it costs a few bucks. WAAAYYY more than tapping into the stock (narrow band) oxygen sensor. At some boost pressure, the engine will "cut out" like you're hitting fuel cut... that level depends on a lot of things including the model year of the car. Basically, the airflow sensor, the firewall mounted boost pressure sensor (pre-87 cars only), and the main ECU (computer) may not "comprehend" big boost numbers. The "1G MAS" upgrade installs an airflow sensor that can comprehend airflows corresponding to big-boost. The "fuel cut defenser" and the "diode mod" trick the boost pressure sensor into seeing no more than stock boost levels. Of course when you "trick" the system, you've got to add fuel some other way or else your air:fuel ratios will dive into the lean region (lots of extra air, no extra fuel) which = blown up engine in seconds. Adding extra injectors, controlled by some add-on computer or mechanism, is the typically approach. Replacing the factory injectors with "bigger" or higher-flowing injectors is 100% wrong way to go - yes, you'll get more fuel during high boost so the air:fuel ratios will be okay then... but off-boost, which is 99% of driving, will be mega-rich and that too destroys engines. You need extra fuel ONLY when you feed the engine EXTRA AIR.

 

The in-dash boost guage is only the computer's estimate of boost too; in addition to a real air:fuel guage you'll need an accurate boost guage. Don't push a factory -12a turbo to beyond 15psi; all it does is make really hot air (it's inefficient) and it'll wear out quickly. A few psi above stock/factory is safe on most "healthy" StarQuests (the air:fuel guage tells you that), going 5psi or more above stock though is much more risky. You MUST know what you're doing and have the aftermarket guages to monitor the health of the fuel system.

 

Instead of adding horsepower, another technique is to use Colin Chapman's method (of Lotus fame): add "lightness." Taking weight out of the car does wonders for performance. Simple weight reductions:

* remove the engine balance shafts with a "balance shaft eliminator" (BSE) kit. This reduces engine weight and the weight of stuff spinning so the engine will rev up/down quicker/easier. When you mash the gas, the power will go to the crankshaft and wheels rather than to spinning up these heavy shafts.

 

* Install an aluminum (Fidanza) flywheel. Some folks have a bunch of weight removed from the non-clutch side of their stock flywheel but that can be dangerous if not done properly. Busting flywheels are NOT pretty - they'll cut the car (and your legs) in half in an instant.

 

Many folks have built up the stock throttle body setup, getting more HP at each step. And working around the factory computer, sensors, airflow issues, etc... then when they finally make the jump to multi-port injection (MPI) and the totally different intake manifold setup they're blown away at how much easier it gets. MPI removes a lot of restrictions and roadblocks in the factory setup. You might want to spend some research time looking at the MPI forums and the stories folks have posted; you may be better off saving $ now for an MPI upgrade later... rather than spending it on oodles of throttle body upgrades and then tossing all that work for MPI anyway.

 

mike c.

[torquebird]

thank you all for the information it is very enlightening. i may tinker a little with the throttle body set up for now just for fun but i will start saving for the other system i have built several cars in the past so i know i have to take baby steps and be careful not to damage the engine. if i were to purcahse the balance shaft elimination kit and jet valve kit to they come with instructions or should i review my service manual on the matter? also i talked to a gentleman yesterday who builds a lot of mitti. cars he said his friend may have an old manifold that would be like running to throttle bodies and four injectors with a piggy back computer has anyone hear of this??????

[patra_is_here]

thank you all for the information it is very enlightening. i may tinker a little with the throttle body set up for now just for fun but i will start saving for the other system i have built several cars in the past so i know i have to take baby steps and be careful not to damage the engine. if i were to purcahse the balance shaft elimination kit and jet valve kit to they come with instructions or should i review my service manual on the matter? also i talked to a gentleman yesterday who builds a lot of mitti. cars he said his friend may have an old manifold that would be like running to throttle bodies and four injectors with a piggy back computer has anyone hear of this??????

 

 

well it sounds like he's describing a multiport system of some sort. but, if it'll actually bolt to the starion engine is a whole other question.