Ok guys.. I don't want to hear the pros and cons or start a debate in regards to anything that is better or cheaper than ordering and installing the Big Bore Kit. I only want to ask one question. How much horsepower can one expect to gain from this modification? thanks
Motorsport Big Bore Kit
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If the only mod you do is the stroker kit, the HP gain will be minimal. This is assuming you are starting with a 2.8L. You will gain a bit of torque, especially in the low rpm's. However, the HP gains are magnified when other upgrades are added in as well. Bang for the buck, this is not the way to go. Plus, you can get all of the parts from a wrecking yard a lot cheaper than Motorsport. If your engine is stock, I would recommend other upgrades like intake, exhaust, cam, etc. before you do a stroker.
Ian
Ian
numbers vague
The actual number varies 50-75 or so (maybe a research rat can find solid examples for you) on a stock L-28 '75-'78. The increase in displacement is almost a direct ratio to power. The biggest gains are on the low end and the loss is obviously lower red line.
The actual number varies 50-75 or so (maybe a research rat can find solid examples for you) on a stock L-28 '75-'78. The increase in displacement is almost a direct ratio to power. The biggest gains are on the low end and the loss is obviously lower red line.
Are you referring to the Weber big throat throttle body or the stroker kit?
I've heard the throttle body can net as much as 9hp, but you can improve breathing by converting your AFM to a turbo AFM body and a better air filter.
The stroker kit increases displacement, so given the same compression ratio and camshaft, your power increases will be direcly proportional to your displacement increase over stock.
I've heard the throttle body can net as much as 9hp, but you can improve breathing by converting your AFM to a turbo AFM body and a better air filter.
The stroker kit increases displacement, so given the same compression ratio and camshaft, your power increases will be direcly proportional to your displacement increase over stock.
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Re: Doesn't lower redline...
The stroker will rev comparably to a stock L28.
The HP gain is not really something you can forecast. Ir really depends on what you put into the whole buildup like said above.
I've seen tweaked SU's on a 3.2 make 170HP, and with thriple mikuinis the same formula made 224HP (both to the rear wheels). The Mikuini motor had head work and a cam, with a big, fat, lazy power band that peaked at 5800, while the SU car was running up to almost 6300 for the power, and was a bit peakier.
Displacement really isn't as important as head modifications and induction mods. The stroke makes you more low-end torque which is how most Americans drive the car, while for HP, you simply need headwork and upper-end mods to the intake to allow higher revs,.
The stroker gives you torque, not necessarily HP. Torquier engines people seem to like better than high-hp peakier smaller engines.
Throw in a turbo, and then it all gets skewed around!
The stroker will rev comparably to a stock L28.
The HP gain is not really something you can forecast. Ir really depends on what you put into the whole buildup like said above.
I've seen tweaked SU's on a 3.2 make 170HP, and with thriple mikuinis the same formula made 224HP (both to the rear wheels). The Mikuini motor had head work and a cam, with a big, fat, lazy power band that peaked at 5800, while the SU car was running up to almost 6300 for the power, and was a bit peakier.
Displacement really isn't as important as head modifications and induction mods. The stroke makes you more low-end torque which is how most Americans drive the car, while for HP, you simply need headwork and upper-end mods to the intake to allow higher revs,.
The stroker gives you torque, not necessarily HP. Torquier engines people seem to like better than high-hp peakier smaller engines.
Throw in a turbo, and then it all gets skewed around!
About those Mikunis...
Hiya Tony.
You wouldn't happen to know what sort of jets they were running in that motor, do ya? I've got PHH44's and my 3.0l motor will be up and running soon, but the carbs are jetted for 2.8l. All of the archive info basically says to run to Rebello. I gave him a call, but the basic message he gave me was to bring the car to him and for a price he'd set them up. Sounds fine to me, but I'm concerned about driving down to Cal. running too lean on a freshly broken-in motor.
Thanks for any info you've got.
Q
Hiya Tony.
You wouldn't happen to know what sort of jets they were running in that motor, do ya? I've got PHH44's and my 3.0l motor will be up and running soon, but the carbs are jetted for 2.8l. All of the archive info basically says to run to Rebello. I gave him a call, but the basic message he gave me was to bring the car to him and for a price he'd set them up. Sounds fine to me, but I'm concerned about driving down to Cal. running too lean on a freshly broken-in motor.
Thanks for any info you've got.
Q
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40,978 Posts
Re: About those Mikunis...
General Rule of thumb is that properly sized jets will flood out an engine changing two jet sizes up. You could simply ream your jets for the trip, content in the knowledge that you will be buying a set anyway, or have Dave send you a set to drive down on with exchange when you get it on the dyno (so you only pay for the jets once...)
Offhand main jet sizes in the 145-160 range should be more than enough, air correctors in the 180-220 range, but much more importantly the idles should be AT LEAST 55's if not 60's.
It is the IDLE system you drive on at cruise speed (slightly under 3000 in top gear) and they must have big jets to allow for tip-in, with the accel pump doing the rest until the main circuit gets going.
General Rule of thumb is that properly sized jets will flood out an engine changing two jet sizes up. You could simply ream your jets for the trip, content in the knowledge that you will be buying a set anyway, or have Dave send you a set to drive down on with exchange when you get it on the dyno (so you only pay for the jets once...)
Offhand main jet sizes in the 145-160 range should be more than enough, air correctors in the 180-220 range, but much more importantly the idles should be AT LEAST 55's if not 60's.
It is the IDLE system you drive on at cruise speed (slightly under 3000 in top gear) and they must have big jets to allow for tip-in, with the accel pump doing the rest until the main circuit gets going.
"There's no replacement for displacement." Remember your 3 C's: Cubes, Cam and Compression. This type of mod gives you displacement and higher compression. As long as you use keep your head the same with a comparable gasket whenever you up the displacement you up the compression. The displacement is potential for power but compression is the most potent mod. I would expect your compression to increase substantially and your power to hit over 200 at the crank. Make sure to increase your carburetion accordingly.
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