A blower on a stroked car? (in over my head)

[67stangboy]

OK, Before I even go into my semi technical thingy I just want to give the disclaimer that im not the smartest person in the world and I still have ALOT to learn about engines so feel free to rip this post to shreds.

I was just wondering if it is worth while to put a blower on a stroked car. My reasoning for doubting the usefulness of the blower is just because if I understand it correctly a blower trys to over come the engines vacume so that it can force air into the engine, which brings with it more gas. And stroking an engine is increasing the engines natural vacume allowing it to move more air in one cycle, (ie. the change in CUI from 351 to 408) Im sure a big enough blower could over come the vacume and still feed the engine even more air but is the money worth the gains at this point? But then again people strap blower on big blocks too and they have a greater vacume than a stroked 351 so my entire thought pattern is probably wrong.

LOL like I said im in way over my head and figured I would see if you guys could help me understand the workings of the engine stuff.

 

[reenmachine]

Ok, I'll take this one

OK, here's the basic idea in simple terms. That is not by any means meant as an insult to your intelligence, it's just that the principles behind this are pretty basic.

Forced induction (supercharger or turbocharger) crams a ton more air into your combustion chamber than would normally find its way in there. More air means more oxygen, which is what your vaporized fuel requires in order to burn when zapped with a spark. More oxygen means more efficient, energetic combustion, which gives you more power. Almost any engine can benefit from it, regardless of size. Top fuel dragsters use giant superchargers on their giant engines to help make their 5000+ horsepower or whatever sick number it is these days.

Hope this helps.

 

[Route666]

I understand what you mean about it not being worthwhile, but it would be. You'd see the same 50+ percent increase on a stroker as you would on a smaller motor, it'd just have more power to start with. Of course with FI, you should lower your compression, which takes away some of that pre-blown power.

If you want extreme power, go for it, but beef up the suspension to put that power to the ground.

Oh and as for top fuelers, there was a comp on in Sydney a couple of weeks ago, and they were making 8000+hp. The overall winning team apparently DE-tuned theirs, to keep it on the track or something.

 

[reenmachine]

Route 666 no more...

Just as a note -- there is no more Route 666 here in the southwest! As of 2003 it's Route 491. Not quite as interesting, but a lot less road sign thefts -- this was probably the main reason they changed rather that at the demand of religious types.

 

[mdjay]

It's worth putting a supercharger on anything designed to handle the forced induction. Forged pistons, low compression to start, I beam rods, stud girdle, cam in the same range as the boost etc, etc. For a stroked car, it's just that much more displacement!

 

[rbohm]

yes, the more air you can cram into the combustion chamber, think of your engine as a large air pump, the more efficient it will be. adding a supercharger allows more air to be pumped into the engine, thus creating higher cylinder pressures, thus allwoing the cylinder to do more work when the fire is lit.

i think i see another related question coming from you 67stangboy, and the answer is no, higher compression helps, but a supercharger moves more air than the higher compression can(higher compression also has an increase in the vacuum you can pull, but not much). you have to consider that air pressure at sea level is 14.7psi. when you add a supercharger that pumps out 6 psi boost(actually backpressure, but i will explain that in a bit), that means your cylinder pressure under boost, and before the mixture is compressed, is now closer to 20psi. you cant get that with just an increase in compression alone.

boost pressure by the way is actually the amount of backpressure in the intake system. if you build a supercharged engine with stock heads, and set the boost pressure at say 10psi, and make say 450hp, then when you substitute a set of higher flowing aftermarket heads, leave the supercharger alone, you find that your boost pressure has actually dropped because of the freer flowing heads, sometimes as much as 4psi in boost pressure, BUT the horsepower has gone up on the order of nearly 100hp. why is this? the freer flowing heads allow more air into the cylinders to begin with, and thus boost pressure falls off, but hp goes up.

 

[67stangboy]

Wow thank you guys for the info. Im trying to learn all of the technical workings of a stroke engine and of a blower and trying to really understand them before I consider doing either. Most likely I will start building a stroked 351w before spring but the blower is still up in the air. I can't decide if I want to keep the stock look of the hood and have it still look mild or if I just want to french the hood and have a big ole' chrome blower sticking out of it. plus ya know their is always that pesky problem of cash.

 

[Route666]

Just as a note -- there is no more Route 666 here in the southwest! As of 2003 it's Route 491. Not quite as interesting, but a lot less road sign thefts -- this was probably the main reason they changed rather that at the demand of religious types.

Yeh I know, I was reading some article on the web about it. I wouldn't be surprised if theft of signage was the reason for the change. Anyways, back to topic.

 

[67stangboy]

Does any one have links to any tech articles on building a stroked engine. If the funds stay how they are I may be able to start in december but I need to learn alot before I even think of picking up a wrench.

 

[D Durden]

First, what are you going to do with it? Is this a drag car, a play around on the weekends car, or a "crap, I need this to get to work" car?

If you trip over stacks of money in your house, I think you'd be better off with a conservative, beefy Windsor, fuel injected, NOT stroked, and blown to about 8 psi. It will fit under your hood, sounds great, and power is NOT a problem. It also has some longevity.

If you have to have this car WORK for a living i.e. it's going to work, let me suggest a normally aspirated 409 stroker. They're 500 HTG horsepower day in and day out. They're robust, and they'll "move that thing" when called for.

For a car that doesn't have a trailer for REAL transportation, you might want to think twice about some 600+ horsepower beastie. Yeah, they're cool and all, and they make the teenage boys get all "woody". Can't beat them for that. As a matter of fact, I've driven my car over to help guys work on them . . . every weekend . . . when they break the transmission for the 4th or 5th time. Or the axle. Or twisted the frame . . . etc.

For a street car, 400 horsepower is a lot of love. 500 horsepower that you can use is a sight to behold. Anything over that starts hurting the driveablity . . . unless you have lots of green paper to toss at your project.

 

[67stangboy]

This car is for shows and car cruises only. It sees maybe 3k worth of miles a year. Right now im 99% sure im going to build a 408 stroker. The Blower is just an idea for down the road. I got the idea from some of the guys that ive seen at Shows in the STL area, mostly older guys who drive their cars about the same milage as I do and store it the rest of the time. They mainly run big blocks, stroked and blown, mainly in chevy's.

 

[mustang2]

reenmachine ???

Just as a note -- there is no more Route 666 here in the southwest! As of 2003 it's Route 491. Not quite as interesting, but a lot less road sign thefts -- this was probably the main reason they changed rather that at the demand of religious types.

I remember that well. I grew up in Kingman, AZ, now stuck here in NC. Hey reenmachine, do you get to Lake Havasu any, there was once a 72 Gran Torino Sport that roamed the streets of Havasu, it was the best looking Torino I have ever seen. Red, with the I believe orange laser stripes.
Awesome

 

[bmcelhinn]

Static compression and and displacement determine how much air an engine will naturally draw in, and fuel mixes with air so the more air and fuel, the more power.

Forced induction whether turbo or supercharger crams more air than the engine would natrually suck in. So it isn't fighting vaccuum, it's boosting it.

So if some guy with a supra like me brags that their 3.0L 6 cyl motor makes more horsepower than 99.9% of the V8 domestics that we run into on the street on a day to day basis they are full of BS, because with turbochargers their displacement is actually increased drastically yet artificially.

 

[reenmachine]

So if some guy with a supra like me brags that their 3.0L 6 cyl motor makes more horsepower than 99.9% of the V8 domestics that we run into on the street on a day to day basis they are full of BS, because with turbochargers their displacement is actually increased drastically yet artificially.

That's an interesting point. I try to stay away from those pissing matches, but next time I'm forced to participate maybe I'll bust that one out.