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This is my very first post at hotrodders. I came across these forums doing research and I was impressed with the friendly and informative experts and enthusiasts that post here. Hopefully I can get some new info about my options here.

I'm looking to add a new powertrain to my 67 Camaro. It has the original 327 with a powerglide. I want to turn this mild mannered pony, into a fire breathing street rod that will run on pump gas and not break the bank in fuel costs. Should be easy huh?

My original thoughts were to use a 6 speed with dual over drive (6th at .62 or .5) to help with fuel economy. Then build a low compression 350 with a twin screw supercharger to try and balance economy and power. The fuel economy could be acceptable with the bypass valve open on the supercharger (no boost). When running with full boost I would get the horsepower I need so badly. Twin screw chargers have been shown to be more efficeient across the entire rpm range than roots or centrifugal.

So, how do I build an engine capable of handling the additional boost, without breaking the bank. And is a 350 really the way to go? There seems to be a lot of favor on these boards for the 400. It has been over a decade since I have built an engine, so any thoughts/help would be appreciated.

Anyone?
 

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Never heard of dual O/D...............enlighten us..

Superchargers don't work that way. With the bypass, as you call it (do you mean wastegate) open..............you get no power.....nada....zilch.....................
You might want to look at a turbo.
 

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Dual overdrive is usually a six speed, where 5th gear is overdrive (.8 to one or so) and 6th gear is even more overdrive (.62 to one).

As I understand it, most of the Richmond and ZF 6 speeds like in the 'vettes have this feature.

I did hear about someone changing out the gears in a richmond so that they had .8 to 1 4th, .6 to 1 5th, and .5 to 1 6th gear, becuase they had a super-torque low rpm big block.
 

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Discussion Starter #4
The Tremec T56 (93-97 F-Bodies, Dodge Viper, and the Aston Martin Vanquish) is a OEM transmission that has dual overdrive. Similar to the Richmond. Good strong reputation. Depending on the year and original auto it had a .62 or a .5 sixth gear.

Almost all superchargers now have a bypass valve that keeps the supercharger from supplying boost at low rpm (I don't know about older variations). They are vacuum actuated, so that at low rpm (high vacuum), the engine simply operates on vacuum intake without boost. You do have parasitic loss because you still have to turn the thing, but you aren't running with the extra power and fuel consumption all the time.

From Eatons website:
"The Eaton supercharger system incorporates a specially designed bypass valve, which is actuated by a vacuum motor near the throttle body, and recirculates the supercharger air flow when boost is not required. During typical driving conditions, the engine is under boost around 5% of the time, which means the remaining 95% of the time the engine is under vacuum, allowing for better fuel economy and a quieter ride."

I think it would be theoretically possible to have the bypass valve controlled by a vacuum assist pump rather than just intake vacuum. I don't know but the thought is interesting. It could also be possible to use an electric clutch to completely take the supercharger out of the loop, but that would depend on the type of supercharger, and the clutch. Just theory...

Still, it seems to me that a supercharger is a good way to try and balance both power and economy. Even though you have parasitic loss, it isn't going to be the hog that full boost or constant high compression would be. If I am not understanding all of this correctly, I would love to get more feedback.

Does anyone have any advice for building a small block chevy for this kind of setup. The engine would have to run at a lower compression, but be capable of handling very high compression without destroying itself. I was thinking about a 350. I have heard that the 400 had cooling issues, and wasn't as reliable a base as a 350. I would love to hear peoples own experiences here.
Thanks..
 

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400`s don`t have cooling issues, they do when other heads are used and the steam holes aren`t drilled. when set with the right pieces, there just as reliable as a 350. If I was after street performance with mileage, then I would find a 96 or up Vortec block that uses a factory roller cam and go from there, this is the same platform I`m following, I plan to use 10:1 compression on pump gas, but I know a few tricks of the trade to make this possible, power and mileage is also my plan. for street performance as well as mileage, you need lots of low end torque, going with the OD tranny already has the right idea, as the lower the rpm cruise band the less fuel used. it`s best to land a cruise speed around 1700 rpm in OD with a carb, but don`t use a cam that`s powerband is above this or it kinda defeats the purpose, you can go lower than this cruise rpm wise with fuel injection. You could follow this same pattern and use a TPI or other fuel injection kit and help all the more. Do everything you can to lower resistance engine wise, make all the low end torque you can, add royal purple diff lube to cut rolling resistance, and power and mileage will be at the tap of the pedal.
 

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The easiest way to get the power you are looking for is to get the best flowing set of heads you can find. That way, you dont have to run big compression or large cams in order to get good hp. I would build a 8.5:1 383 with AFR 195 comp package heads, and a hydraulic roller cam somewhere in the 230 @.050 range. Then run a supercharger at around 10-12 lbs of boost with an intercooler. Consider this setup:

AFR comp 195's

NX276HR cam

P1 or F1 procharger with an intercooler at 10-12 lbs boost

on a 383 o4 406.

this combo could be run on 89 octane, and would make around 700-750 hp.

You could get a smaller head, and cam also.

Adam

Adam
 

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Discussion Starter #7 (Edited)
Thanks DoubleVision, this is pretty interesting. Is this something you have working, or is it still a work in progress? I would be interested to know how much HP/Torque this setup generates across the RPM band.

Lots of questions:

I am not opposed to fuel injection, I just don't know as much about it's aftermarket use in hotrods as I would like. Is anyone running a hotrod with a fuel injection system they are really happy with?

I like the idea of gaining efficiency by lowering rolling resistance, honestly not something I was thinking of at this point. Any other tricks to help the whole process be more efficient? I came across an article in a recent Hot Rod about coating engine components in heat resistent, or teflon based materials. Has anyone done that in their own ride?

What is the basis for this general idea that 400's are not as reliable and don't cool as well as a 350? Does anyone know if they had problems originally what have been since corrected?

Since it seems that you think lower band power and torque are the goals I should be shooting for, would a stroker be a better approach?

Thanks...

Thanks firestone, thanks for all the detail. This is exactly the kind of thing I need to know.

I was thinking about paying for some really nice Brodix heads, because it is going to have to breathe if I put a supercharger on it.

The supercharger I was thinking about was the Whipple. The twin screw design is still pretty new to automotive use, but it seems like a really efficient setup more capable of generating power without the need for an intercooler, because it doesn't heat the air as much as a roots style.

Isn't a 383 basically a stroked 350? I have never been that fond of stroker engines, but maybe I have been wrong all this time.

How much compression are you estimating that this engine would have at 12 lbs of boost? How would I avoid predetonation without retarding the timing?
 

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Discussion Starter #9
I have thought about an LS1 briefly, but I don't know anything about them. I saw a good deal on one recently and almost got it. What can anyone tell me about the LS1?

I don't like automatic transmissions very much. I definitely want a manual. Plus I feel like i'm going to want an overdrive, so I might go down to a 5 manual, but probably not. I know eventually I will want a 6 speed...

I need to research the LS1. Any good links?
 

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I am running a Tuned Port Injection unit on my 66 gmc (not really a hot rod as they are generally seen but . . .) and I love it. I picked up about 3-4+mpg from my carb setup and I love the instant throttle response and torque I have. Not to say I couldn't have had that added power with a carb, but it wouldn't have come with the added MPG. They aren't as hard to set up as one might think and the benefits are great. If you are looking into power and MPG I'd look at a modified TPI (as the stock dont really flow past 4600RPM), an LT1 or LS1 type setup, or something along those lines. If you are going fuel injection, go multiport. I personally wouldn't waste time going from a carb to TBI.

http://www.ls1.com/

LS1's are potentially (and stock for that matter) VERY powerful engines. Its what the pre-2005 Vettes had as a base and now that the corvettes are going to have the ls2, GM is moving the LS1 into more of their other performance vehicles.
 

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Discussion Starter #11
The only problem I have with TPI is the cost. I would rather spend my money on a supercharger and good heads... Unless someone knows of a cheaper TPI than I am seeing.
 

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From what I have seen, a whipple and a procharger produce about the same amount of heat. If you ran a whipple or procharger at 12 lbs of boost and no intercooler, with 8.5:1 compression, you would have to run premium fuel. If you ran a procharger at 12 lbs of boost with an intercooler, you would be able to run 89 octane at full timing, and the inlet air would be cooler which would make more hp. As far as heads go, the brodix heads are good, but you will need ported heads to get what you are after. You are looking at between $1000 and $1500 for a full professional port job. That being the case, you will have around $2200-$2700 in the heads. The comp AFR heads are already fully CNC ported from AFR, and flow like a professionaly ported set of brodix heads for $2000 a set. If you dont want to spend that kind of money, you can get a set of street CNC ported AFR heads for $1300. They are still 100% CNC ported, the comp head are just ported with more precision. 383s are a good idea, they make more hp and torque, especially at low RPM.

Adam
 

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Discussion Starter #13
That is great advice. I will look at those heads instead. If they flow that well for the cost it is worth it. That is exactly the kind of thing I need to know before I start spending...

I was confusing the procharger with a root style blower. Does the procharger make as much power at lower RPM's. My understanding was that the centrifugal superchargers weren't as good at lower RPM's as a roots or twin screw. Is there a significat cost difference between the Whipple and Procharger?
 

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It is true that the roots and screw type superchargers do make better low end power, but that is not to say that a procharger will not have good low end power. It depends on your powerband, if you build it to make power down low, it will. The thing about street cars is that power down low really isnt a problem, usually with street tires in a situation like this, there will be no way to hook the car up anyway, so a little more on the top end and a little less on the bottom end isnt the end of the world. As far as cost goes, I dont know what a screw type costs. I have heard of people getting supercharger/intercooler packages from procharger for under $3000. Check out their website.

www.procharger.com

Adam
 

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Discussion Starter #15 (Edited)
The topic of superchargers in specific is very interesting to me at least. To hopefully get a more detailed comparison, I started a new thread for superchargers specifically:
http://www.hotrodders.com/showthread.php?s=&threadid=53913

Some of you have great information on the subject.

This thread has provided a lot of good information, and taken me in directions I wouldn't have originally gone: Strokers, Centrifugal superchargers, TPI...

Firestone makes a good point. With a 383, I will already have plenty of low end power. I don't really need to focus there with the supercharger.

I am wondering what else I should consider when specing out this engine. I don't really want to dump $20,000 into the engine alone, so how do I meet my goals without breaking the bank? It still looks like a supercharger is probably the way to go, but there are still so many unanswered questions: What type of supercharger, fuel injection or carbueration, big block or small, should I use a stroker engine, and what kind of heads or internals do I spend the money on?

All of your feedback is appreciated.
 

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The Richmond 6-speed does not have two overdrive gears. Fifth gear is 1:1, and 6th is an overdrive. The T-56 has two ovedrive gears, with fourth being 1:1.
 

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If you are after a large gear spread, take a look at a gear vendors setup. It is like a split axle, it will give every gear an under or an over, which will double the amount of gears you have and make each gear closer together in ratio. Plus, shifting from under to over is done with a button on your shifter, and you will not need to clutch during this shift, which helps on the dragstrip. You will not need the 6 speed tranny with this setup, a 5 speed will work fine and still give you the double overdrive. The under for each gear is a 1:1 ratio, and the over for each gear is a 0.78:1 ratio. You could either get lower cruise RPMs or go with numerically higher rear gears to gain more acceleration and still be livable on the street. They say the unit is guaranteed to 1200 HP, and is only like 12" long.

www.gearvendors.com
 

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Discussion Starter #18
I heard about these a few years ago, but I never understood them. I guess it is time to brush up. I wonder how a 5 speed with a gear vendors unit would pair up in a price and performance comparison with a T56. I have seen the T56 for less than $1,500 rebuilt. Forgive me for over simplifiying this, but is it like a second transmission sitting in front of (or behind) the your primary?
 

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MadJester said:

I am not opposed to fuel injection, I just don't know as much about it's aftermarket use in hotrods as I would like. Is anyone running a hotrod with a fuel injection system they are really happy with?

My turbo engine is EFI. I like it so much I will probably never build another rod that is not injected. I am a gadget guy who works in the building controls industry so electronics dont scare me. It is the future of all kinds of hotrodding. I think one day Holley will sell 50 types of EFI and 2 types of carbs instead of the other way around.

Chris
 

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Mad Jester,

To me your spending alot of money to gain a few mpg. Your going to have to drive alot of miles before you get any mpg pay back.

How about a much simpler, lower cost method to start:

8.5/1 compression, strongest bottem end you can,
retard/ timing adjustment in the car,
all the nitrous it can handle,

now you can cruise on 87 octane, use lots of timing for a better burn, best cost per mile/mpg

hit the nitrous button, go like ####.

You do know motors so I didn't add any details.
 
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