2.0 8V Volumex Race Engine Build - Help?

Competition engines and ancillaries - general discussion
MACAuto
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by MACAuto »

Now that here are more members in on this thread, I offer 2 more questions for this group. The kit I am evaluating has a non-standard crank drive cog. It is my understanding that the VX was offered with two drive cog combinations - 29 teeth on the crank combined with 22 on the blower, and 29 teeth on the crank combined with 21 teeth on the blower.

The particular kit has a 33 tooth crank cog combined with the 21 tooth blower cog - a drive ratio of 1.57. Any good guess what boost pressure that will produce?

Guy, will your offered 1" belt with 93 teeth fit on that combination? (The NOS belt needs to be replaced as it is more than 15 years old...)

I have settled (for now) on a bottom end build using forged 8:1 flat top pistons, with Carrillo rods, and suitable valve reliefs for my 46mm IN X 40mm EX valve head. A 3-quart Accusump will be piped directly to the main oil galley, and the oil cooler will be increased in size to a 20 row. Radiator is a custom 3" thick copper/brass unit. Cams will be GC 3A IN and 2B EX. The Weber 45 DCOE will be tested with both 30mm and 32 mm venturis, and full form 50mm tall velocity stacks. Comments are welcome.

MACAuto (Bill)
Guy Croft
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by Guy Croft »

I've already remarked on drive ratios so I will not comment further.

As for kit, hardly anything I do is a 'kit', I can supply various belt lengths, 93, 99 typically, its up to you to place my tensioner on the back of the belt bolted in the best position to secure it.

You won't get the engine to work right with 32mm chokes so it's not even worthe testing, start with 30mm and if she doesn't 'pick up' when you 'blip' * the throttle (off load) go straight to 28mm. Going smaller is the rule in this case, not bigger.

G

* for anyone who is wondering why I use inverted commas so often it is because these well-known British phrases will typically be unintelligible to non-English speaking members; you certainly won't find them in adictionary (as such) or Thesaurus - as used in the context of our discussions. Other members might do well to follow my example...
volumetrico
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by volumetrico »

Hi
Thats only going to raise boost a little
I think the standard setup is 6psi, therefore assuming my maths is correct:

Original setup 29/21 = 1.38
Modified setup 33/21 = 1.57
Boost/driven ratio 6/1.38 =4.34
Revised boost 4.34*6 = 6.82psi

I forget how many teeth are on the cam wheel (46?). If you could make something up to use that on the bottom, you would get closer to 9psi. I think the choices/pully combinations are dictated by belts available.

Not sure what effect that would have on durability (25% faster). The compressed air would also be hotter.

I believe Guy now recommends against over spinning these blowers from the standard setup (they are getting rare now). Kinda linked to my earlier post about Eaton blowers, they are cheap and plentiful enough, allowing less mechanically sympathy ! Also a custom install allow one to consider using chargecoolers or intercoolers, something that cannot be done using the OE setup.

Guy, just picking up the intercooler point above. Does the blower have to be run in any particular orientation? ie can it be run upside down? Would running it on its side could also be possible (assuming correct placement of external oil feeds) ?

Below is something I considered a long time ago. If you mount the blower upside down and tilt it a bit (it will physically mount upsidedown) , this could just about allow use of an intercooler as 'boost side' would now be facing forward and air could then be routed through a cooler and back into the OE manifold.

I realise this would require some work/fabrication
- to secure the blower properly (no longer bolted to the manifold, only using the lower bracket)
- you'd have to convert the manifold to use injectors
- get filtered air into the blower
- route boosted air into the OE VX manifold
- think the oil resevoir can just be turned around, or if running on side would need dual feeds (also consider breather)

Melo
GC #162
Guy Croft
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by Guy Croft »

Without fear or favor and before this blower speed thing goes too far!

1. std VX road engine std 29/21 ratio @ 6500 rpm blower speed 8976rpm

2. race engine 29/21 ratio @ 7500 rpm blower speed 10,357rpm

3. race engine 33/21 ratio @ 7500 rpm blower speed 11,786 rpm

Now that assumes peak of 7500rpm which is nothing in racing even for a blown engine, indeed the power may be still climbing, so why cap it? We'll see.

Now the powerband is dictated by 1) gear ratios 2) diff ratio (incl wheel size) and engine power. These should be the primary inputs B4 the question of blower ratio is EVEN considered. I would never wish to be seen as being patronising but I don't think this has been thought-thru yet, though knowing Bill it will be. All I am saying is that the blower speed is a secondary issue and should be set aside for now and if you want my advice is is spin it as slow as you can or else find a good supply of spare VX blowers. Which you won't because the vintage MG fraternity have smashed most of them up by running them direct off the crank on methanol. You really don't need to work out the rotational kinetic energy in those heavy VX rotors (except know that it varies as the square of speed) to figure out the faster you spin them the more likely they are to go 'out of phase' for any particular reason. Eg: bad backfire. And take the whole engine with them. They are not keyed or splined they are held together by Act of Parliament. And running the blower faster may just result in uncontrollable wheelspin at low speeds, I have seen how savage this can be from a dyno test.

More modern blowers have lighter rotors some even plastic (Nissan). Eaton blowers are OK if brand new but there are some charlatans selling them so beware. They are a throwaway blower, trust me. They are helical and you CANNOT overhaul them because once they leave the factory they are impossible to re-phase.

GC

edited because part of it didn't make sense..
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all that keeps the rotors running they way they should, ie: in phase, is 2 nuts.
all that keeps the rotors running they way they should, ie: in phase, is 2 nuts.
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you have to be extremely careful where you place the necessary lubricant to torque them up. Get it in the wrong place and the rotors will slip out of phase (locking and causing massive damage) and if you don't lubricate the mating face of nut & washer and thread you'll never get the right amount of preload - resulting in the same,er 'sticky' end.
you have to be extremely careful where you place the necessary lubricant to torque them up. Get it in the wrong place and the rotors will slip out of phase (locking and causing massive damage) and if you don't lubricate the mating face of nut & washer and thread you'll never get the right amount of preload - resulting in the same,er 'sticky' end.
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robert kenney
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by robert kenney »

Let me preface my statements by saying that I have not VX blower experience persay but extensive race blower experience from drag racing and high performance street.

The VX is a straight rotor roots type of blower and the VE / adiabatic efficiency curves for these diminish rapidly above 9500 blower rpm. Above that the power required to spin them goes up more quickly than the power they will make largely due to heat and rotor tip speed.

I don't know what the rotor to rotor clearances are but watch outlet air temps when not running fuel through the blower as the rotor expansion will lead to internal contact and sure destruction.

I would recommend investigating stripping the rotors with Teflon if more is needed. This assures a good seal, more aggressive pressure curves especially at low rpm's allowing lower blower peak rpm's and heat. The striping also helps stabilize the rotors and inhibits contact so long as the blower is restriped regularly.

Regardless I would stay below 10500 at any case if drawing through and less if injected down stream of the blower.
Robert Kenney # 111
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by Nobby »

Thanks for the explaination Guy - a pic means a thousand words.

I've absolutely no experience with the VX blower, but is it not possible to modify it so the nuts can't undo themselves or so the gears can't move? Possibly a dowel into the shaft then remove a small chunk out of the inner gear.

Do they have to be left as is for historical racing?
Chris Burgess
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Guy Croft
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by Guy Croft »

Given that if you put them together right (and I must have done about 40 of them over the years) they are reliable, I have to say that I have not explored any alternative method. It would, I suppose be possible to 'put' some kind of pin or key thru the gear and shaft but it would be a hugely costly op. And you really would not want to do that on an old unit (maybe when new...) because the backlash in the gears varies and I have to allow for that when 'phasing up'. Not the least costly since you'd have to 'pin' the gears to the shafts and they are hardened. 'Retro' things like that rarely work - they have to be designed in from the outset.

Correctly assembled, I have only known one go 'out of synch' due to a major (ignition induced) backfire where the backfire valve was stuck solid.

I do a fair bit of polymer coating (when folk can afford it, it's no 5- minute job) but apart from that it really is 'run as-is'.

G
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by MACAuto »

Guy,
You wrote - "I would never wish to be seen as being patronising but I don't think this has been thought-thru yet, though knowing Bill it will be."

This exercise is certainly part of the thinking-thru process, and I don't at all feel patronised. Applying forced induction to any race engine is a costly undertaking, and proper planning of the technical aspects of the project is essential. It would be foolish to push forward without determining a clear and attainable goal.

If I am to build this VX engine, I will have to find a 29 tooth cog for the crank. I will also have to limit engine speed to 6500 to 7000 rpm, to avoid over-speeding the blower. In the end, I don't believe, based on the available examples offered on this thread, and from other sources I have found, that the engine can make the power I will need for the class I will be competing in. It seems that, even with my above mentioned build specs, the power output will only be about 180-190 HP, most likely BHP, and not WHP. Torque will likely be 175 to 190 at the crank, which is certainly more than my present race engine, but again not enough to make the car as competitive as I want. Another factor is that I don't want to possibly ruin a rare classic Fiat/Lancia performance piece for the sake of trying to apply it to a duty beyond it's design criteria.

It will be 'back to the drawing board' for a turbo-charged race engine. My shop has the expertise to do that build, as we do it nearly every week. It would also be far easier for my crew to fabricate/construct the necessary sub-systems for a turbo engine, using the varied and plentiful components available in today's marketplace. If you believe that it would make for some interesting 'thinking-thru', I can start a new thread to review the design considerations of a 2L 8V TC turbocharged race engine build.

MACAuto (Bill)
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by Guy Croft »

Whoa a minute Bill.

I think: This spec is going to develop 200bhp or a lot more. As you know even an well-sorted atmo 8V at 2050cc (never mind big-bore) can do that and here we're blowing the air in. The supercharger adds power doesn't take it away! But more importantly it will deliver over 180lbf ft torque. Maybe a lot more. And that torque curve will likely be near horizontal from 3500-6500 with plenty in had beyond that.

And there won't be any lag, the throttle response will be lightning. And on E85 who knows how high the ordinarily rather low supercharged CR could be taken? Maybe 10/1 or higher? **

This is what I think - the proof is dyno I know that. I'm not going to guess at exact figures but I would expect a build by me to exceed 220bhp comfortably. Even very mildly tuned VX units running OE cams of various types on 45 DCOE that I've done have exceeded 200bhp at the wheels.

You could go down a class and supercharge a 1600cc by the way...

In my expert opinion it makes no sense whatever to bin this concept in favour of turbo. But you're the boss..

G

** I would welcome comments on the CR on ethanol mix.
wmausbach
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by wmausbach »

Bill,
One final note. I have no experience with High Performance VX but my Friend Stan does. He sold me his Volumex when he got a 037 version. He built a street VX that pulled 190hp. The HP chart was still going up when he shut down the dyno run because he had basically a stock bottom end and he was afraid he blow it up on the dyno. He did overspeed the blower but he had made this engine for a street application.
Wayne in Houston[attachment=0]Stock VX vs Stan.xls[/attachment][attachment=1]dyno2Stan190HP.jpg[/attachment]
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MACAuto
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by MACAuto »

Guy,
I am still keeping this plan alive, but I have 2 issues that will need to be answered:
1- I don't have any source for a 'stock' 29 tooth crank pulley.. Any help or source out there?? I understand that to keep the VX from failing, I will need to limit it's speed to about 9000 rpm, which impacts the maximum engine speed. 6500 to 6600 rpm engine speed (with 29X21 gearing) is something I can govern, either by rev limiter in the HPV-1, or a sharp eye on the rev counter by me.

2- What WOULD be a practical limit to increasing C.R., considering the use of E85? I will need to order pistons, and will want to get the right ones. I understand the politics of using food to make fuel, and am closer to your thinking than you might imagine. It is my understanding that those in bio-technology are working as I write to allow in the near future for ethanol production from waste materials (a good thing) - even waste vehicle tires (tyres). I just can't help liking the great characteristics of E85 as a race fuel. Much better for the air than leaded racing gasoline fuel. My shop's testing of this fuel for racing is nothing but positive. As for use in a street car? No money will be saved as the fuel mileage is awful. It's why I have a 15 gallon fuel cell in the Spider.

NASA's (National Auto Sport Association) Super Touring 2 class is power to weight derived. The racing weight of my 124 Spider (Bill included...) is about 2070 lbs., and my adjusted P/W is 9.2 NASA measures by Wheel HP, so 225 WHP is the goal. Torque isn't factored in the classing, so any supercharger will be an advantage over N/A, or Turbo.

Wayne,
Very nice to hear from you. Long time. I will have to let you know when I plan to race again at Texas World Speedway. Thanks for the help. Can you find me an alternate crank pulley for the VX?

So, Crank Pulley, and how high on the CR? Any help will be very welcome.

MACAuto (Bill)
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by Guy Croft »

For crank pulley you could use the VX one and I may be able to procure and original VX front pulley (unless some kind soul here has one already for Bill). They are two-piece and you can press-off the water pump V drive section and shrink an toothed-belt drive onto it for water pump and alternator - or just leave it off altogether if you are on electric pump and no alt.

As for CR - if I was doing this - given the potential for using higher CR on E85 (due to its higher knock resistance and charge-cooling effect - am I right about that? I am no expert on that fuel) - at least based on what I have been told, I might be tempted to run maybe 10/1 static CR. I know you can 'get away with' 9/1 CR on 97 octane RON on a VX provided you have cool ducted intake air. It might be a good idea to instal something like Omex mappable ignition (with a trigger wheel perhaps mounted on the VX drive pulley) with a manifold pressure sensor.. dunno really.

Some of this is actually uncharted territory for me.

Can anyone shed any light on this from their own experience please?

G
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by Guy Croft »

VX front pulley pics - pressing off the V section and what's left fitted on a crank nose.

This is the 1600 VX for the Triumph Spitfire featured on the site albeit that Matt, the new owner of the project has had a revised dry-sump bracket made.

G
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engineerted
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by engineerted »

Bill,
A good example of a supercharged engine running E85 would be the Lotus Exige 265, yes this was a test setup but they are running 11.5 cr with a super charger and getting real 260 RWHP numbers from a 1.8l motor. I realize that the Lotus (Toyota) engine and the TC are not the same but for comparision sake, you might consider using your current motor as is, with the 11.2CR and just use the VX cylinder head and blower but with a 1:1 ratios drive to keep the boost low and run some test for knock and power. There are drag racers out there running these type of CR with E85 and boosed. Just some thoughts, as Guy states this is "uncharted territory".

Ted
74FP SCCA 124 spider
MACAuto
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Re: 2.0 8V Volumex Race Engine Build - Help?

Post by MACAuto »

Guy,Ted,
Two replies that are combining with the discussion at my shop that are producing echos. My dyno tuner has tuned more than 500 different turbocharged vehicles with E85. He has found, that even on boosted Subarus, which are extremely prone to detonation, that there is much higher knock resistance and charge-cooling effect with E85. He has already told me to use the existing bottom end, head, and bolt up the VX with the milder cams, and make sure there is enough fuel delivery. He also insists that the air/fuel mix will also cool the blower itself.

But 11.2 CR on a Fiat 8V TC? I wouldn't attempt to waste anyones time here if I thought this was feasible, which is why I started this thread. I really didn't expect the discussion to arrive at this (albeit reserved) conclusion. I believed going in that this project at the very least would involve a bottom end build with lowered compression.

If there are any more opinions about this, I would appreciate to hear them. Would a 1.38 drive ratio be out of the question? (What am I asking?...) Are there gearing sets available more towards 1.0? I really don't know what to use, other than VX related pulleys, and I just don't have any source for these bits.

As far as Ignition is concerned the Electromotive HPV-1 I have is mappable to a certain degree. It has a rotary selector to set initial advance, a second selector to set additional advance to 3000 rpm, and a third selector to provide for additional advance (or retard) from 3000 to 8000 rpm. The crank trigger wheel is bolted to the crank pulley. The water pump is driven without idler by the crank pulley. There is no alternator, or any other belt driven ancillaries.

MACAuto (Bill)
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