8V71 vs. 8V92

[MacRon]

Considering an 8V92 on a big block Chevy, mounted on a tunnel ram, (going for the looks). Properly built BBC (454 or 496) with around 700HP for the street on pump gas. Just wonder if the 8V92 is too big. I'm going to convert the blower myself. 92 cores are cheaper than the 71's. Would like to spin the blower less and keep it cooler. My inspiration is from this video: https://www.youtube.com/watch?v=sAMi7PZPeVk&t=104s Any help would be greatly appreciated.

[mag2555]

700 hp starting from what 400, or 500 hp?
You need to think about carb placement it terms of the fuel bowls ( slosh) with them up so high and cornering on the street!

[DaveMcLain]

Aren't the V style blowers more difficult to use for other purposes because of how the case bolts are angled instead of straight?

[Newold1]

I think you might end up spending more money and time on trying to use the 8V92 blower than just finding a nice already polished 871 setup on the used market that has already got a manifold , pulleys and carb setup that someone has already setup and used and then removed from their engine with low hours. It sounds like you are itch'in for a project, but this one might be more than you might think to complete. If you want more than an 871, there are probably a good quantity of 1471's out there in a complete state also. These older ( old school) style blower setups are falling from favor with all the new Whipple and turbo setups so they are not bringing big bucks in the used aftermarket. Try Racing junk.com, Yellowbullet.com classifieds, maybe Ebay, etc. JMO

In any event have fun with whatever project you've got the itch on! Enjoy!

[mag2555]

Yes, that too !
I don't know what if any off the shelf Manifolds there are for those?

[DaveMcLain]

Many times good used blowers that are larger than an 871 can be had cheaper than the smaller ones which seems counter-intuitive until you think about how much easier it is to fit an 871 or smaller blower in more applications.

[wyrmrider]

Whose tunnel ram
been there did that for a street roadster
you need to brace it except for maybe some early heavy cast tunnel rams
we had no pop off valves and blew it all to hell

[MacRon]

I've done the research and all of the drive assembly, front and rear plates are interchangeable with 8-71 and 8-92 blowers. The tunnel ram is an Edelbrock 7075 and the pop-it valve can be mounted to the front. The adapter plate is available on eBay. I appreciate everyone's concern, but this is a very do-able, economical project. Estimated cost is $1,500 vs. $3,500 for a store bought blower. My question here is the volume difference between an 8V71 and an 8V92. Nothing shiny about this project. It's a 32 Ford sedan, air bagged to the ground, engine reaching for the sky, patina with rust and aged bronze, Darth Vader's Rat Rod. It's a show car, not a racer.

[DaveMcLain]

I asked a friend and he said that the 71 and 92 series are different blowers. First of all there is no stock 871 blower all 871's are aftermarket. The 8 cylinder 71 series engines were all 8V71. There was no 6 cylinder 92 series engine they are all of the V configuration. Many of the 92 series blowers are the bypass type that bypass when the turbo is spooled up..

[tresi]

Well, Since it's not a race car and you're going for the something different look why not? But if happen to have one and trying to build a blower motor on the cheap be prepared to spend twice what you think you're going spend any time you stray off the beaten path. It cost money to be a trail blazer.

[Dave Koehler]

The 8, both 71 and V put out about 440 CFM per rev. in stock form.
No, it's not too much. That is why they make different pulley diameters.
Going to be one looong belt though.

[Krooser]

I put together a complete blower set-up for my last Hemi project... had less than $1500.00 in it. I bought five 6-71 blowers off of old engines... $20.00 each. I had a blower shop do the gas conversion for $450.00. Found a NOS Cragar intake on the shelf of an old speed shop in MA for $300.00. Used a big block Chevive kit that was on ebay... snatched it for $300.00. These deals can be done on the cheap...

That said I would not mess with a v style blower... those ebay adaptors are of questionable quality... at least the one's I've seen. Find a used intake... they are around. Visit a big truck salvage yard or keep you eye's open on-line for a good core blower. A 6-71 will give you all the power you need... the extra length of the 8-71 is all at the back so you may need to find an offset dizzy which you won't need with a 6-71.

Make sure you get a good cam that will be streetable yet have the zip you need. George at Clay Smith ground my Hemi cam... very mild but with lots of grunt.

[t120r]

Considering an 8V92 on a big block Chevy, mounted on a tunnel ram, (going for the looks). Properly built BBC (454 or 496) with around 700HP for the street on pump gas. Just wonder if the 8V92 is too big. I'm going to convert the blower myself. 92 cores are cheaper than the 71's. Would like to spin the blower less and keep it cooler. My inspiration is from this video: https://www.youtube.com/watch?v=sAMi7PZPeVk&t=104s Any help would be greatly appreciated.

I noticed no one really answered your question... The difference in an 8v71 and 8V92 are as follows: 8v71 come in big bore rotor configuration with 'small bearings' and usually the end plates can be unuseable due to no thru bolt holes (hit or miss). The 8V92 can be big or small bore and big or small bearing and every one I've seen has the through bolt holes on the end plates to really clamp it down. Both big bore 8v71s and 8v92s flow the same as the rotors are almost identical except for the shafts. I believe that's 448ci/rev. The small bore 8v92 will flow less, but I've yet to find out that number. It would be nice to find one and do the calculation on it. The small bearing end plates are interchangeable between both blowers, but the big bearing plate can only be used on the rear of the 8v71s. That's all I can remember off the top of my head.

For a conversion the 8v71 looks better as it doesn't have that big wide upper intake flange. The 8v71 flange is almost bang on 6" which makes fabricating a carb adapter easy.

[Alaskaracer]

The 8V71 and 8V92 are not blower designations. They designate the engine they are fitted to. Detroit Diesel two strokes ran them, the engines wouldn't run without one. 8v71 stands for an 8 cylinder, V configuration, 71 cubic inches per cylinder. 8V92 stands for 8 cylinder, V configuration, 92 cubic inches per cylinder. On the 6-71, and 4-71, they were used on inline engines, 6 cylinder and 4 cylinder, 71 cubic inches displacement per cylinder.

I don't know how much difference in displacement per blower there is, but that's how they are designated.

[Dave Koehler]

We need to start a pool.
Did the project progress past the what if stage?
Did he go with a V blower or wisely use a standard 671 or 871?