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Discussion Starter #1 (Edited)
So, my current engine is a 358 cid SBF. it is a 4.090 bore by 3.4" stroke at 9.0:1 compression. With 20ish psi of I/C boost, the car runs low 5.40's high 5.3's in the 1/8 at about 130-131 mph on a 26X 8.5 tire. Currently on Pro E-85 with only 6 passes on that fuel. During the winter I added a boost controller and took the Saleen wing off in favor of a Scott Rod rear wing. I have 4 years on the current combo, with only the valves being upgraded due to the wrong valve being installed originally by AFR. Car has a 4.10:1 rear gear (8.8) a glide based trans, (Reid case 1.80 gear) car weighs 3150 with me in it (as per rules). Question is: going to a 4.125 bore brings me to 363 cid, maybe going to 10.0:1 compression as I can not get more boost with the current blower, and upgrading the S/C would be 3-4 times more costly than going 363 and 10.0:1.

I know the current combo with the upgrades of boost controller and rear wing "should" net me a 5.2 ish run, is it likely that the added compression and displacement (5 cid) could be worthwhile? For the $, at this point should I go higher compression than 10.0:1? The block is good for up to 380 cid, but I don't want to spend the bucks on a new crank and rods. An overbore and pistons could net me maybe 370 cid. But the 370 cid combo does not leave me much room for any further overbore, the rest of the cid would have to come from a 3.5" stroke, lots of $ at that point.

Thoughts?
 

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you are reaching the point of diminishing returns


the dollar/speed ratio is climbing

a larger dis twin screw makes the most sen$e
 

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Discussion Starter #3
you are reaching the point of diminishing returns


the dollar/speed ratio is climbing

a larger dis twin screw makes the most sen$e
Except that the larger twin screw is a lot more expensive than just the blower. My entire inlet and outlet manifolds were designed around the existing S/C. Changing to a larger screw blower would require a custom intake manifold, which my friend did on his car when he went from the 2.8L KB to the 3.6L KB. The Hogan intake manifold was just over $4,500. Add in the 3.6L KB with the inlet and throttle body is $6,300. So just around $11k to upgrade the S/C. Not cpounting the misc stuff that gets thrown in, so at least $12-13K to play that game. That is a lot of coin. Albeit, it would get me another 10 psi of boost which nets around 300 HP or so. I was hoping to get an extra 150 HP or so to keep me in the ballpark in the HP wars, out in left field, but still in the ballpark. Some of the other racers are in the 1,600-1,800 HP range and all I can do is hope they lose traction on the hit and give me a chance. Lol. I just don't know if going up in compression and displacement will net me 150 HP, maybe it would. IDK. I do know it would "only be $2k or so to do. Not the $12K of the bigger S/C.
 

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Discussion Starter #4 (Edited)
Here is a 3.6L KB on a SBF. Not a direct swap.



Here is my current set up, 2.8L KB with air/water I/C



With the BOV installed as a boost controller

 

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you can go with a 12.1 compression we did it a Kenne bell on a mod motor and pickup a bunch. How is Walter car running with the 3.6.
 

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Discussion Starter #6
you can go with a 12.1 compression we did it a Kenne bell on a mod motor and pickup a bunch. How is Walter car running with the 3.6.
What kind of fuel were you using at that point? I am committed to using Pro E-85 at the moment (have a barrel of the stuff) I could switch to Methanol and get rid of the I/C which would net about 2 psi of boost. Thing is with the Methanol, I would have to run a second set of fuel injectors and get a mechanical pump and all that it entails. Plus I think that without the second set of fuel injectors being in individual runners it could lead to some distribution problems.

Walters car is getting there. Last Thursday it was on the dyno but they could not keep the tires from spinning. Netted 980 HP at the tires and then went into severe tire spin. Guess is around 1,200 to the tire. Got one hit at Pacific Raceways Sat evening and managed a 5.42 @ 133.87 with some issues with the car on the big end. I am sure it will run a pretty decent number once the bugs are worked out. The 3.6 is making 31 psi in the current configuration.
 

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Discussion Starter #8
How much boost on that 12.0:1 Mod motor?
 

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Discussion Starter #10 (Edited)
Good to know. Whatever I end up doing will be after this season.

As far as running Methanol, after giving it some thought, I could buy some 325 lb/hr injectors and that way not to have to run 2 sets. Or run 2 sets as I already have 220 lb/hr injectors in the engine, and have a spare set of new 120 lb/hr injectors that could be set up to run in the side of the Reichard Racing upper manifold that currently houses the I/C core.

This is the I/C core that could be removed if switching to Methanol



Here is the Reichard upper that currently houses the I/C core. Thinking I could fab up some Runner dividers that could slip into this upper, they would come up about 2/3-3/4 of the way to the top.



Then the extra set of fuel injectors could be mounted into this side of the intake. Make a custom fuel rail that is one piece that holds all 8 injectors'

 
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