2.0 8V Volumex Race Engine Build - Help?

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

Post by MACAuto » Tue Feb 08, 2011 8:29 am

Guy,
I am posting to discuss my best options (some good advice, please) to build a new race engine for my road racing 2.0 8V124 Spider. I will be moving my Spider upclass in NASA to the Super Touring 2 class where the power to weight ratio, as the chassis is equipped, is 9.2 to 1 (Racing Weight to Wheel HP). Racing weight is with driver (me), and is 2070 lbs. That makes my target HP 225 Wheel HP (with estimated 15% drivetrain loss, the target HP at the crank is nominal 265 HP). NASA - National Auto Sport Association - classes most cars by power to weight, so utilizing Forced Induction is a good way to optimize power in a given class.

I had considered turbocharging, but that would have required a conversion from my present Webers 48IDFs to EFI and new EFI management. Also a new exhaust manifold, the turbo, reduced compression pistons, cams, intercooler and piping, and more, would be needed. After reading some on this site, and after making inquiries to suppliers for the proper conversion parts, I lucked into an available Volumex Blower System - complete. So, my reason for this thread is to gain the knowledge and references needed to complete the build of a 2.0 8V Volumex race engine.

I assembled the present engine, which is a 2.0 8V with twin 48IDF carbs with 42mm venturis, feeding a race preped head with 46mm inlet and 40mm stainless valves, GCRE 5A/4A cams, GCRE triple springs, GCRE pattern Venolia 11.2 CR pistons, Carrillo rods, custom 29” primary runner 4:1 header with 1.75”primary size, and wet sump with 3 qt. Accusump, 16 row Mocal oil cooler. Engine control is by Electromotive HPV-1 direct crankfire ignition. Fueled with E85 (85% Ethanol - 15% gasoline) pump fuel, this combination yielded 176 WHP, and 136 Wheel Torque (206 BHP, 160 torque, at the crank). Great power, and great fun, but off on power to the rest of the class, with no practical way to class downward by ballast, or any other means. I need forced induction.

In addition to the Volumex system, I have a sound 2.0 Fiat 132 shortblock to build with, which is compatible with the 6-bolt Volumex mount. The HPV-1 will allow mapping for boost retard, and will be retained. The Carrillos will be retained. I would seek to retain one of the 48IDFs to feed the blower. I also have another race prepped head with 43mm inlet, and 37.5 exhaust valves.

My questions for the members, and for Guy:
Can I make 265bhp with the core parts I own (excepting the pistons and cams)?
What will it take to achieve that figure if it is feasible, and would the boost level be within the working range of the VX blower?
What CR pistons are required for this build?
What Cams will be needed to make this work?
What other details need to be addressed (oil cooler capacity, radiator capacity, exhaust pipe size, etc.)?

Regards,
MACAuto (Bill)

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

Post by Guy Croft » Tue Feb 08, 2011 10:07 am

MODEL POST!

Ignoring tech comments for the moment I just want to say that I like this one. A clean clear and concise post with 1) need and 2) call for a solution.

Look forward to members remarks.

GC

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

Post by engineerted » Wed Feb 09, 2011 3:50 am

Bill,
I don't have any real answers for you, but I have read a few things about the Volumex blower and it seems that you are only going to get 6-8psi boost from it. Trying to boost it any higher will cause some excessive heat issues. Either way, this sound very interesting. What are you going to do for the drive line? Trans? Rear end? This is some serious HP, not to mention the possible Torque!


Ted

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

Post by MACAuto » Wed Feb 09, 2011 8:31 am

Ted,
I have heard of 200 and some BHP, and 190 Torque for a street Scorpion/Monte Carlo with the VX blower on a 2.0 8V, from something more than 8 psi. I have also heard that the VX will boost over 10 psi. But I am posting here for better information.

The thread on FS.com is for something very different from what I plan. The drive train I have now is very reliable, utilizing the 131 gearbox, and a 7.25" racing clutch. A special tri-link rear suspension with wishbone lateral location keeps the power I have now glued to the tarmac, and returns very predictable handling over the stock 4 link/panhard configuration. I do worry about the mid 70's style live axle, however. No problems with 205 BHP, but the expected increase in torque is an unknown with that differential.

I just want to determine if the power I will need is possible with the VX supercharger. The Group B Rally cars produced far more power than I need, but used a different Abarth Supercharger. The available kit I am looking at is NEW (NOS), and complete.

As I mentioned, I am posting here for better information.

MACAuto (Bill)

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

Post by Guy Croft » Wed Feb 09, 2011 1:55 pm

I really do not know how much is possible from an 8V TC VX supercharged unit in full-race trim. There is a simple and reasonable explanation for this, I have never done it. I am sure that to capitalise on the full potential of the unit one would have to use the fabled 'blowing down' method where radical overlapping is employed to achieve optimum cylinder purging, cooling and thus filling. I understand that this can lead to er, 'healthy fuel consumption' and I surmise furthermore that there could well be a 'bottom-end' torque penalty.

However I think it's worth a go since it's not just bhp that counts it's torque too and the only engine size for size as fast in acceleration as a supercharged one is, well, another supercharged one. I don't want to make any any further engine v engine comparisons though.

Insofar as using current equipment is concerned the main changes will have to be cams and pistons and I would not recommend use of an 48IDF I would use a 45 DCOE.

As for the survivablity of the rear axle the only way to find out is to try it.

I assume a conversion to the (reversed port layout) 16v head from the Interale/Tipo series is out of the question? I see no reason why one of those with the right (I mean GC) setup should not fly past 260bhp with over 175lbf ft.

G

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

Post by MACAuto » Wed Feb 09, 2011 10:08 pm

Guy,
Thanks for the reply, which brings to my mind a few questions. You mentioned: "the fabled 'blowing down' method where radical overlapping is employed to achieve optimum cylinder purging, cooling and thus filling." I'm not sure exactly what this means. Does this have to do with cam selection, specifically relating to duration and overlap? If so, which cams do you recommend for this build?

As far as the 45DCOE is concerned, what venturi size do you recommend? 38mm, 40mm? I will mention that using E85 fuel requires uprating fuel delivery by about 20-30 percent, but that I DO have a 15 US Gallon fuel cell in the racer.

With respect to the pistons, given the duty of this engine for sprint races (30-40 minute duration), what compression ratio do I need? 7.5:1CR seems very low, even given the pressures the VX will generate. Would 8:1CR or even higher be appropriate for this racing engine? Please know that the present engine holds together very well with the high compression race pistons, using a Turbo head gasket, and ARP head studs, torqued to 72 Lb/ft. Never had problems with head gaskets. Even so, I would want to build with the most appropriate head gasket for this supercharger, and I will need a reference for that gasket.

I wish my budget for this build would include a 16V head, but it doesn't. I believe that with my few queries answered, I will be able to move forward with this build. Please help with these remaining issues, and any other suggestions or concerns that come to mind.

The worst that can happen is that I will wind up with a potent engine - not for my race car - but for my street 124 Spider. I hope taking the proper precautions, and preparations, will make this less of a "roll of the dice".

MACAuto (Bill)

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

Post by Guy Croft » Thu Feb 10, 2011 11:20 am

Bill, overlapping is a deviation from the accepted cam practice employed on less highly tuned supercharged engines, where we'd ordinarily have minimum overlap and lift at TDC on inlet and ex valves. This to maximise power stroke and keep fuel use to a containable level. Moreover blown engines don't use pressure waves for tuning and so overlap of cams to generate them betw ex and inlet tracts is not needed.

With overlapping we give more of both and deliberately blow the charge to flow right across the chamber around TDC at the end of the ex phase. Charge will flow (and be lost) to a far greater extent since the valves are open further and for longer. This is not to create pressure waves it is to clean the cylinder (purge the residuals) and cool it to assure optimum new charge density. The effect of charge contamination will be To an extent the engine will (so I think anyway) behave in a manner not disimilar to an n/a unit whereby you get more benefit the higher you rev it - exactly as an atmo unit with radical cams; of course you have the add-on advantage of overboost too.

For cams I'd start with a billet combo like GC IIIA inlet and IIA or B ex. This gives big inlet event with quite high LATDC and more modest ex which is about right when you're 'testing the water'. It might be possible to go more radical but I would only change one cam at a time to find that out. You are in rather 'uncharted territory' I'm afraid and it will be interesting and at times perhaps dissappointing to explore. I don't have dyno stuff for things like this because no-one has ever asked me to do it.The closest comparison is a standard VX (even std head and 7.5/1 CR) with 45DCOE and just a GCIIIA inlet with low loss straight-thru silencer system where the owner in Germany reported that even that made his VX Coupe faster than his 8V Integrale.

The 45 DCOE will need small chokes, likely 28mm, 30 tops. If the choke is too big it will not 'pick up' at all.

CR 8/1 should be OK. On E85 you'll have to explore fuel delivery rate and mixture control 'real-time' I have no idea what will be needed. Inlet charge temp needs to be kept as low as possible so a fully sealed ducted air intake is needed drawing air from an aerodynamic duct on the front spoiler. A large K&N filter should go in that system betw carb and front intake. These setups can suffer carb icing at high humidity and below 12deg C so consider a warm air feed if running in those conditions.

A comparable head gasket setup to that which you're using currently will not cause any problems. The header should be 1.75" bore primary (much bigger than ports) 4-1 and 36" long. The tailpipe downstream of the collector should be 2" bore. For mufflers I'd recommend 2 x AX891 which I stock and which you can find by search on the site.

I certainly suggest very strongly that you avoid any temptation to spin the blower any faster than 1.32 x crank speed. The VX is held together by goodwill and friction and the rotors are prone to go out of phase with catastrophic results. You need a direct-drive 1" belt to run it which will mean making a tensioner like the one shown.

I know you have excellent facilities and skills but I do have inlet manifold for horizontal DCOE, belt and tensioner among other things if you want them.

I hope this 'gets the ball rolling'....

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

Post by MACAuto » Thu Feb 10, 2011 6:27 pm

Guy,
Thank you for your replies. This does get the ball rolling for this project. I will be sending a email inquiry to you for the items you have mentioned, that I will need. The kit is set up for the standard 1.32 drive, but lacks an idler/tensioner. I will need to find (from GCRE?) a source for 8:1 forged piston set for the 46IN, 40EX valve head.

My Shop has a rolling road AWD chassis dyno, to get the tuning right, and a fabrication "department" (in the corner...) to handle the header fab. We will use schedule 10 stainless in either 304 or 316, as I have a supplier for the shapes, and the collector. No bigger than 2" on the tail pipe? I would have thought bigger, as that is what I have now for the N/A engine. 103 decibels at 50' is the noise standard at most tracks, so the exhaust is without any mufflers.

We have found E85 to be an extraordinary race fuel. Fully 40% of the EFI tuning we perform utilizes E85. The extra volume required is the puzzle for tuning, but also a great benefit. It is truly a "cool fuel" and should provide some needed cooling for the VX. Subsidized by the Govt. and (don't hate me) priced currently at $2.30 to $2.70 USD/USGallon (1.43 to 1.68GBP). Leaded race gasoline is $8.00 to $10.00/gal., and the E85 burns cleaner, and gives more power.

I will update my progress as this moves forward, if there is interest.

MACAuto (Bill)

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

Post by Guy Croft » Thu Feb 10, 2011 7:10 pm

OK

You can go bigger on the tailpipe but the AX891 can handle all the power this engine can give and is only 2.25" ID so there is no point at all going over 2".

BTW - I am 'anti' ethanol fuels because of the general environmental impact it's production has. Crops_4_fuel. Madness. I am very pro-hydrogen however and one day when all the oil has been burned and there is no oil left to lubricate even a sewing machine some might be given cause to wonder why it was not explored intensively in the time we had left to do so. Its suitability, for example, for rotary (Wankel) engines is hardly novel, my professor at University proved it out for Mazda in the 1980s.

G

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

Post by volumetrico » Sat Feb 12, 2011 10:19 am

Hi Bill
Interesting thread. Just to pick up on one of your points regarding 037 blowers/power;
The 037 R12 'volumetrico' supercharger fitted to the roadcar is probably around 30% bigger than the R10 volumex version, although it does share the same size ports and mounting pcd/bolt pattern as the volumex version, it's obvious it flows a lot more air for a given speed.

The works car R18 version is bigger again! And has bigger entry/exit port area (3 ports instead of two).
Works 037 Evo's also used water injection (don't know if you had considered that?)

From memory, I think the early works 037's (non Evo spec) using the R12 were around 260bhp and I don't think they were able to use water injection on the non Evo cars.

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

Post by Guy Croft » Sat Feb 12, 2011 11:21 am

I've driven an EVOII for which I rebuilt the engine, a genuine Works one. 15psi boost & fuel injected of course, no water inj. What the BHP was I have no idea, but I can tell you that the torque was so phenomenal & instantaneous that during acceleration it reached peak rpm so quickly I could simply not change gear fast enough, in effect I never had time to explore anything like the potential of the engine. Never exp that since.

G

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

Post by volumetrico » Mon Feb 14, 2011 11:46 am

I'm pretty sure I know the car you drove and the ex-owner sometimes comes on here.
I remember having a discussion with him about the absence of water injection and the answer was along the lines of "keeping things simple and not chasing every last bit of power to keep things relaible". Water injection was homologated for the EvoI and EvoII cars, but I guess it may not have been used on everything. I also know that Abarth had wanted to use it on the earlier non-Evo works cars, but FIA would not allow it as it wasn’t on the road car.

I wasnt aware that the EvoII runs that kind of boost. Pretty impressive given lack of intercooler. I guess it would be interesting to understand the relative flow/ air temp differences for each of the blowers at a stated speed (Volumex, Volumterico, Evo1, Evo2) as boost dosent tell the whole story. I understand I am unlikey to ever see that data. The Evo2 blower at 15psi must also take a fair bit of power to drive it !

Given the rarity of the Abarth units, I wonder how the Eaton blowers fitted to various Kompressor Mercs compare (I dont think these have ever been discussed on here). These seem far better value than the Abarth units (assuming someone is starting from scratch with no manifolds/ mounts etc) and more readily available.

I havent had the fortune to drive a works Evo, but been lucky enough to have a ride in the Safari spec works car that’s in the UK. It was great fun, not to mention the noise :-)
A road car is going to be so dissapointing by comparison !

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

Post by Guy Croft » Mon Feb 14, 2011 12:15 pm

It was Fred Holloway at the time but that was 1996

G

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

Post by cstorry » Mon Feb 14, 2011 6:06 pm

A road car is going to be so dissapointing by comparison !
Melo


Melo - I would never turn down a ride in an 037 Stradale : ) nudge, nudge
In the meantime I have to make due with my integrales.

I'm looking at how to fit my R12 to the reverse "reverse-port" 16V head Guy mentioned a couple weeks ago - infinately more affordable than the Abarth 16V head.

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

Post by volumetrico » Mon Feb 14, 2011 10:08 pm

Guy, sorry, I was thinking of another 037, not Fred Holloways (chassis #28)
#28 was originally a road car which had a EvoI engine added at some point along with other work and the Martini paint. Later an EvoII engine was fitted (presumably by you).
Looks like a great car to drive !

Here is the water injection manifold that was homologated with injectors visible (I guess this wasnt always used).
http://www.abarth.co.uk/forum/037/037_w ... ection.jpg

Chuck - will send you a photo/ email in a bit.

Melo
GC #162

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