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Discussion Starter #2
Engine Info:
2.5L 1st gen
1992 head
crank from OMC boat motor
corods from nova
350 pistons shaved .040
454 injector
2 bar MAP sensor
custom intake system
custom header

I live in California, so I deal with SMOG. It takes about 45 min. to completly convert it back to stock.
My dad made this.
 

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I like, I like. I bet the turbo spools in no time flat
 

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No i've never run it on the track. If got a borg warner 5 speed like what came in it but its the world class version. But the tubro was only like $150 cheap china crap. And its a little bigger that what we want. But if it works out really well i might eventually put in one that is a bit smaller so it will come in at a lower RPM. I'm running 6 or 7 psi and it probably putting out 160 to 180 HP at full boost. Sick.
 

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haha thats awsome!! any idea what your afr's are? how high you rev it up to? And what is this crank that you're using, i've heard of the 153 crank but i'm iffy on that actually working on a newer 2.5...
 

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rizzle, i know i might get laughed at, but what are afr's? I really don't know what I rev it at (am I supposed to have a tach??lol) The crank is from a OMC boat motor, which originaly used the same engine as the novas came with as the base model (yeah most people got the 6 or 8's but they did come with 4's) and then eventually they made there own engines but stayed with the same internal dimensions. There are a few differnent cranks, but this one lengthened the stroke about a 1/4 inch.
TaylorN.
 

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if doing any spirited driving, it's always a good idea to have a tach.

AFR is short for air/fuel ratio. gotta be right or it runs bad. with turbos it's especially critical because the AFR changes wide and fast.

I'm curious what computer and electronics you used...
 

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Right now it has a chip in it made by some guy back east. I think it was like $100. He has them premade that you put on the stock engine to make it run better. For alot more money he can make custom chips for them, but you have to download some software and hook your laptop up to the computer with a interface cable and then email him the info. I'm not sure what the price is but its pricey. I have a 2 bar MAP sensor. Unfortunatly you cant floor it in every gear when going from a stop. 2nd gear is very sensitive, but when you find the "sweet spot" it takes off, but yeah its a bitch. 3rd gear is a little like that but not bad. But other that that its all stock. I'm thinking about taking it to a shop in town with a dyno and seeing what peak HP is. According to the calculations I did before putting the turbo on, it should be about 180 HP. Bitchin'
 

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Hey how much did u bore it out to get the 350 pistons in it and what did u do to the top end of it. i want to do that with mine but with no turbo.
 

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hey what do u have to bore it out to to fit the 350 pistons in it and what do u have to do to the top end cause i want to do that to mine with out the turbo?
 

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Don't get me wrong I'm not knocking what you've done (I think it's awesome actually) but I was just thinking about it (and my main interest is the cressidas which have supra moters in them which swap very easily for turbo supra moters)...if you had an intercooler and all the right supporting stuff (fuel, ECU, etc) 7 psi would get you roughly 150hp at the crank (I'm also accounting for the redesigned intake manifold and larger displacement (bigger stroke crank)) at most which through a manual will run about 120 at the wheels. with, as you say, the running problems I'd be suprised if you hit 100 hp at the wheels.

Before you get all angry at me remember the famous words "HP sells cars but torque wins races". In your current state you're probably hitting 150 or 160ftlbs at the wheels. torque is what you feel when you hit the gas, it's what pushes you forward. HP just means the engine can do it while revving high.

I think your next step oughta be get a megasquirt standalone or something along the same lines and hand it to the programmer/tuner. the difference between what it is now and what it could be is as different as what it is stock to what you've done so far.
 

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Don't get me wrong I'm not knocking what you've done (I think it's awesome actually) but I was just thinking about it (and my main interest is the cressidas which have supra moters in them which swap very easily for turbo supra moters)...if you had an intercooler and all the right supporting stuff (fuel, ECU, etc) 7 psi would get you roughly 150hp at the crank (I'm also accounting for the redesigned intake manifold and larger displacement (bigger stroke crank)) at most which through a manual will run about 120 at the wheels. with, as you say, the running problems I'd be suprised if you hit 100 hp at the wheels.

Before you get all angry at me remember the famous words "HP sells cars but torque wins races". In your current state you're probably hitting 150 or 160ftlbs at the wheels. torque is what you feel when you hit the gas, it's what pushes you forward. HP just means the engine can do it while revving high.

I think your next step oughta be get a megasquirt standalone or something along the same lines and hand it to the programmer/tuner. the difference between what it is now and what it could be is as different as what it is stock to what you've done so far.
ok you said the turbo really increases the torque, now that gets me interested, how if you can theoryize, could i set a turbo up to increase torque but only around the 2000-2500 rpm scale or is this feasible mines a daily driver, and i try to only run around these rpms, sometimes i run close to 3000 taking off, depending on traffic, atlanta is a bitch, go or get run over, would the turbo damage engine running down interstate boosting constantly at 2500 rpm?
 

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well, by increasing torque, you increase HP. HP is just an imaginary mathematical figure of torque plus speed. increasing torque up high will make a more noticeable differnece in HP, increasing torque down low might not actually increase *peak* hp because of the rpm matter.

as far as practical application....low rpm boost is easy. just get a smaller high AR turbo with a good waste gate control and it'll spool right quick. like 1500 rpm or less. with the right setup (electronic or mechanical) you can have low boost, and switchable so little/no boost on the highway (think like a switch to turn on the turbo. or a dial to say how much boost)

the problem is in the inherent design of the 2.5 and it's electronics. 1 bar map sensor only reads up to 14.7psi absolute (aka atmospheric pressure....no boost) and the ECU will be utterly lost. add to that the stock bottom end isn't set up for boost but you can certainly change that. if you ran something like megasquirt for fuel/spark control you'd be set. (I say MS because I doubt there's much support for aftermarket ECUs for the 2.5 and I wouldn't pay for an add-on chip that I couldn't take to WOT and ran like he says.
 

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...the problem is in the inherent design of the 2.5 and it's electronics. 1 bar map sensor only reads up to 14.7psi absolute (aka atmospheric pressure....no boost) and the ECU will be utterly lost. add to that the stock bottom end isn't set up for boost but you can certainly change that. if you ran something like megasquirt for fuel/spark control you'd be set. (I say MS because I doubt there's much support for aftermarket ECUs for the 2.5 and I wouldn't pay for an add-on chip that I couldn't take to WOT and ran like he says.

This interests me because I have a 76 Chevette I'm putting my 2.5L in and I wanted to turbo it... Obviously I'd have to run the computer from the s10, but what is this megasquirt thing you speak of? And what is MS? Also running max of 7.5 pounds of boost, which bar map sensor would I need? Thanks.
 

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to be more descriptive, MS is a DYI fully programmable ECU it's dirt cheap (<$300 for the ECU, <$500 for everything. add 50% for a fully assembled unit) and works well once you get it tuned. the catch is it comes completely unprogrammed. www.megasquirt.info (.com is a VERY different site). one thing you can do to make it easty is find someone on the MS forum with a similar setup and list of mods and ask nicely for their current software programming. it's a beautiful thing for a DIY weekend car. it's not for the faint of heart or daily driver
 

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kamesama980, I like your thinking. No i take no offense. When my dad and i were doing the computations on it before we started building, our aiming point was between 190 and 200 HP at full boost. I know I'm not getting that much, but I'm sure i've got more than 100hp at the wheels. But the biggest problem right now is fuel. I'm running a stock (acctually from a differnet year but still from s10 2.5L) throttle body and pressure regulator. But also, we didn't build this to be a racing machine, just with a stock 2.5 with 150,000 miles on it, it didn't exactly get up and go.

Joecool, the turbo won't boost when going down the road. It only boosts when you put a load on it, ie going up a hill, pushing the gas pedal, whatever. Its acctually pretty neat. I will be driving along and will hit a small hill and I won't have to give any gas and the turbo starts to kick in.
TaylorN.
 
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