Newbie engine block questions.

[willhaven]

I did a quick search and didn't come up with many results, but I was wondering about engine size/weight/power questions. Small blocks are 318-360. Correct? Are the blocks for all of those engines the same size with different bores? Or are they all unique block types with a 318 being a physically smaller/lighter block and a 360 being the largest of them? If it isn't physical block size that separates small blocks from big blocks, is it the engine design?

The reason I'm wondering is because I'm planning to eventually make a street E-body and I'd really like to do a twin turbo setup. Basically I'm trying to work out the smallest engine package necessary to push the strongest Keisler 5 or 6 speed, be twin turbo, run on pump gas, and not guzzle gas too much.

Am I right in assuming that you can make a lighter turbo engine for street uses than using pure cubic inches to get the power I need? I'd want to make the car light in the front end for handling purposes. Maybe I'd use a fiberglass front end, probably a Reilly suspension, and the smallest engine possible.

Any suggestions? I'm probably a good 6-8 months away from starting any serious car searches (need a house first), but I guess it would pay off to know what direction I'm heading before I reach the fork in the road.

Thanks for any help.

[wart1de]

Your correct, 318, 340 and 360s are small block engines and the weight differences between each is marginal at best.

A 340 or 360 can achieve 400-500HP without turbos, so unless you want more than that and have plenty of money to spend then money might be better spent on upgrading your suspension if handling is what your after.

The noise of a twin turbo v8 is nice though.

[Chryco Psycho]

the 360 block is unique from other small blocks as it uses a larger main brg diameter , but the external dimentions & weight are similar , the big blocks are totally different
 how much weight you acn actually save with all the added weight of turbos & plumbing will be minimal at best but you will have the power to push it no prob

[willhaven]

Ok, now, turbo question (or four ). I've heard mixed reports on this. Is it possible to turn off your turbos on the fly for fuel comsumption purposes? It would be nice to, at the flip of a switch, go from a relatively passive 360 with a mild cam to a fire breathing turbo at will. Since the limits on those Keisler transmissions seem to be around 600-650hp, would it be reasonable to expect to do this?

If a 360 can already be pushed to ~500hp as you state (probably with hot cams and all the performance parts in the world attached), might I think that a more passive 360 would put out less, but that the turbo providing around 8lbs of boost would get it near the limits of the transmission? I've read that 15lbs of boost will double the effective power of your engine. I guess 8lbs would add another 50%?

What kind of pressure can you push on regular pump gas? I've also read that, the more you boost, the more likely it is that you will have to use really high octane fuel to keep the compression alone from igniting it prematurely.

As for the cost of a turbo setup, that's what I'm trying to gauge now. Balancing the cool factor with cost, MPG & what the transmission would actually be able to take. I also plan to upgrade the suspension heavily as well. I'm eyeing those bolt on suspension kits from Reilly (front w/rack & pinion) and Heidt (the independent rear suspension).

Also, as a newbie who has never owned a muscle car before, I don't even know what kind of numbers are good for the street. Is 600hp a crazy number to be expecting any kind of control from? I basically want something with incredible accelleration but I don't want to have to fight to not lose traction every time I change gears. But then again... maybe I do.

Thanks for the help so far, and thanks for listening to my innane newbie ramblings. But, I figure a lot of people aren't asking these kinds of questions, so the only way to get them answered is to scour the web forever, or just open my stupid mouth and get some answers here.

[1973challenger360]

can you turn of a turbo,   I guess you can jam a screw driver in the propeler, but then i guess you would be under the hood and not on the fly.     Dont watch mad max vs the thunder dome anymore  roots blowers and almost everything else besides a no2 bottle cant be turned of.  and im not sure turning it off would make u get better fuel milage.

mopar made 2 aluminum small block 318's there were 4 now only 2 left, those are probably out of the picture. 

Turbo's lage/ superchargers dont but the steel hp/ a 7500hp top fuel motors 14-71 belt steels 500 give or take hp a 6-71 around 90.

1 Big turbo spools up slower but makes more power             not always true
2 smaller spool up faster but make less power                     not always true depends on set up
4 good luck fitting them under the hood.
there is a 57 chevy with 8 it made 700hp just for looks.

no one makes a bolt on turbo set up, your best bet would be an aluminum headed 273/318/340/360 or stroked motor with a procharger/paxton ect.   they bolt on and cost way less than fabricating a turbo on.   for $3600.00 for a procharger on a 380hp 360 crate motor there suppost to make over 600hp.

the 273 318 340 all have a 3.31 stroke just different bores.

to achieve the fastest ramp up from lighter pistons try a 273 or most power from a large journal 360 with a 4" stroke or more.

[Follicly Challenged]

You could Mechanically "dump" the boost from the Turbo with a solenoid on a wastegate ? In theory could be done, but this would still leave the parasitic drag on the exhaust flow which is still driving the "dumped" turbo under normal driving.
Pro-charger 

[willhaven]

The turbo is run by the exhaust manifold pipes, so you could technically block it off right? If no exhaust gas enters the turbo, it won't spin and it won't suck any air or extra fuel right? As for turbo lag, apparently if you have properly designed plumbing and the right size of turbos it should be a non-issue. Especially if you use two instead of a single or sequential setup.

I've also looked at Stephen Durr's Challenger. He has a supercharger. Maybe a supercharger would be an easier option, but I believe he still had to have a manifold fabricated. He also had quite a few engine failures before he got it right. Maybe I could learn from his mistakes and go from there. He has a big block, so there might be some significant differences that I am unaware of.

If anyone else has more info or experience with turbo setups, I'd appreciate it. Turbocuda has a TT setup and lives really close to me. Maybe I can bother him when it comes time to do the deed.

[Chryco Psycho]

you would have to build a gate in the pressure side of the exhaust that could withstand 1300* or more to close off the bypass & force exhaust threough the turbo & you really need to fuel inject it , if the carb is between the turbo & intake you will still have to spin the turbo to get air into the carb 
 turbos are relatively efficient as long as your right foot isn`t too heavy

[willhaven]

Yeah, EFI is a must. While tinkering around with a carb setup sounds interesting from a do it yourself mechanical perspective, being able to look at stats and reprogram an EFI sounds right up my alley. I do make videogames for a living afterall.

Is there any downside to an EFI system? Outside of price or difficulty of setup. In terms of performance, are they better worse or the same?

[Chryco Psycho]

EFI propoerly tuned Shouldl outperform a carb , the Only down side is at max throttle sometimes a carb will out perform a carb there

[wart1de]

You will be fighting for traction on the street with 300hp let alone 600hp.

 

[willhaven]

Well, with the Heidt rear suspension you should be able to cram 11" wide tires under the car at least. I don't know how much more traction that would provide. But really, would ~600hp be insanely overkill on the street? If more than 300hp is useless for street purposes, why do so many street cars have big blocks to begin with?

My current daily driver car (2004 Acura TL) gets 250hp at the wheels and it doesn't feel unwieldly at all, even when I gun it. The cars are also similar in size, though the TL is a bit lighter.