Alfa Romeo Forums banner

1 - 20 of 41 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter #1
Just thought I would introduce my self and ask a few questions - I've been reading posts for a few days now since joining this BB. I'm Toby from the UK and I'm half way though fitting a Alfretta 2.0 twin cam '84 engine into a 1970 MGB.

Its a long story up till now but as a bit of back ground info: In my student days I used to have a quick Mini which I killed visiting a long distance ex-girlfriend (lots of 70mph+ motor way driving!). So I bought an MGB but it wouldn't pull a skin of a rice pudding - out came the anchor which had been masquerading as a sports car engine and in went an Mazda MX5 1.6 engine (complete with HUGE GReddy turbo) from a written of track day car from my local scrap yard. The novelty of massive turbo lag soon wore off (at the same rate as the splines on my rear wire wheels) and plans where made to put right my mistake!
<years later>
I've now picked up the project again, older and wiser(?), with the intent of realising my dream to have a classic car that will hold against ever quicker modern cars in an in keeping and characterful way. An updated version of what MG should have done in the late 60's - ditched the push rod, cast iron, 5 port engine in favour of something to rival the competition. I considered the Alfa twin cam as one of the best classic 4 pot engines ever built - and if you can't beat 'em, join 'em! Which is why there is now one bolted to the front of my B's 4 speed + overdrive 'box in my car!

What I'm after is some advice regarding building/tuning the engine, this is what I'm aiming for:
1) 180hp at 6,000RPM or so - I want usable power for the road - not the track (I race a MG Midget for that type of thrill!)
2) reasonable fuel economy (especially for cruising) as its going to be my every day drive and long distance tourer.
3) low end torque to pull 24mph/1000RPM overdrive top gear but with a torque curve that invites you to rev the engine when having some fun around the twisty bits.

This is how I'm thinking of getting this:
Emerald ECU - Well known in the UK - fully programmable fuel/ignition curves with sequential injection, wide/narrow band feedback, 2 stage injectors etc.
A Eaton M45 supercharger built in to a modified Bosch L-jet inlet manifold with a air to water charge cooler.

I'm hoping to use standard pistons (9:1?) and bottom end. If the head has to come off I'll cut 3 angle valve seats and blend the port into the valve throat if possible but other wise standard. I'm also hoping/thinking of using the standard cams (are these the Euro 2000 cam??) with the VVT on the intake cam - the Emerald ECU can control this and would be optimised on a rolling road. I do have an option of buying some 272deg cams (@10thou) and 10.3mm lift but have no idea how these would perform - welcome any experience with cams like this? The VVT seems to useful to pass up - are there any non standard cams designed to be compatible with this? Unfortunately the standard cast iron exhaust manifold wouldn't fit around the chassis so will have to be tubular running into a performance big bore MGB exhaust.

I was disappointed to read that the standard 2.0 L-jet engine is way down on power compared to its DIN standard of 130ish! I now have to consider working back up to what's its supposed to make and then on to what I'm after - I had been thinking of about 7psi boost to give very approximately 40% more power... The M45 blowers efficiency starts to drop off quickly after much more than this with the flow rates necessary for 180+ hp.

I would love to hear any comments/suggestions/criticism (well.. go easy on the last one...) especially about the cams as they finish on ebay in a day or two.

Thanks, much appreciated! Toby
 

·
Registered
Joined
·
4,075 Posts
Hi Toby,

I think your goals are very realistic, probably even low. The three you listed are absolutely no problem at all. The standard pistons with 9:1 compression and stock cams should work out very well.

The M45's numbers look really good for a 2 liter with 7 pounds of boost. Power under the curve will be great. Keep in mind you will be limited to an absolute maximum of about 10 psi with that blower, you could get away with about 12 psi by keeping the engine's redline down to 6500 rpm or less. If you need more boost you will need a M62.

I prefer to bolt the supercharger to the motor and plumb the air to the factory manifold. This essentially insures equal distribution of air to all four cylinders and allows for massive intercooling possibilities and upgrades if you decide to make changes later.

Greg Gordon,
www.hiperformancestore.com

1985 Spider with a MP62 bolted to it. Not running yet due to time constraints, but it looks cool.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #4
Greg,
I was looking to bolt the blower onto the exhaust side of the engine for ease of plumbing, to save having to make extensive mods to the inlet manifold and to make charge cooling much easier - but the engine seems to be totaly devoid of sutable mounting points! Some pics of you'r setup would be great! On the pluss side, with the blower beeing integreal with the inlet manifold and charge cooler, the throttled volume is going to be quite a lot less.
Thanks, Toby
 

·
Registered
Joined
·
4,075 Posts
Hi Toby,

I won't put up any pictures of it at this time. Past experience on Alfa forums has taught me not to put up anything until it's done. I do have some V6 pictures as well as a picture of my Spider's supercharger crank pulley here: http://www.hiperformancestore.com/superchargerkit.htm .

There is some logic in trying to minimize the volume of air the supercharger needs to compress (I am guessing that's what you meant by throttled volume). Bolting the blower to the manifold does help with that. However the benefits are minimal. The volume of air in a 2 inch diameter pipe running across the top of the motor is not significant as compared with the total system requirements. On the V6 motor we have found that for a given supercharger drive ratio boost will be the same with a remote mount vs. an intake manifold mount. That's assuming properly sized pipes on the remote mount setup, and it's within the accuracy we can see on an Autometer boost gauge. So it's not super scientific but it's certainly with .2 psi.

When total system performance is factored in the remote mount comes out ahead due to the greater ease of intercooling.

Greg
 

·
Registered
Joined
·
26 Posts
Discussion Starter #6
Greg,
What I'm getting at with 'throttled volume' isn't really considering the volume of air to be compressed but more the volume of air under vacuum - down stream of the throttle. This volume affects the throttle response, particularly at part throttle, which is why individual throttles on runners give very crisp response. I'm wouldn't be overly worried about this, especially if the pipes aren't too big/long, but it's just another consideration. On the down side, charge cooling is much more difficult! This is why I’m having to consider a compact & efficient air to water heat exchanger. But what swings it for me is the lack of mounts on the 'hot' side of the engine and roughing no1 exhaust down pipe past the back of the blower - forcing the supercharger to be mounted even higher and further away from any potential mountings around the alternator/main engine mount.
I didn’t bid for the cams on ebay in the end… if needs be Newman cams can regrind std cams for under £200 and that way I’d know exactly what I was getting! I also need to listen to a lot more advice regarding caming a supercharger Alfa engine before parting with any hard earned cash…
Toby
 

·
Registered
Joined
·
4,075 Posts
Well with a remote mount you can keep the throttle in the stock location and blow through it. This way the volume downstream of the throttle won't change. Although I really don't think response will suffer at all anyway on a supercharged motor.
 

·
Registered
Joined
·
625 Posts
haha, true that, keep upping it a psi until all the lag in response is gone
 

·
Registered
Joined
·
400 Posts
Not exactly that relevent to your project Toby, but I'm using an Emerald K3 ECU and am working (slowly) toward a supercharger installation on a 12V V6 at the moment...so, I'm interested in this. I'm moderately familiar with the ECU so might be able to assist if you have any questions.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #10
That would be great... sorting out the ECU might be quite a challenge in its self! I've bought a Rover KV6 alloy throttle body to use as the Rover stuff is nearly plug and play and has a throttle potentiometer and idle bypass valve built in. It also happens to be brand new and going dirt cheap on ebay!
Toby
 

·
Registered
Joined
·
380 Posts
By pass

Hi all, Greg, with the throttle in the stock position (asuming a L-jet manifold) and the supercharger on the exhaust side, how do you plumb a bypass for the supercharger?

Thx
 

·
Registered
Joined
·
4,075 Posts
I do that two ways. The first bypass is a butterfly type built into the supercharger and it's totally self contained. However it doesn't react fast enough to prevent pressure spikes in the plumbing during when upshifting during acceleration under boost. To relieve those spike I plumb in a fast reacting valve from a Porsche 993 turbo between the supercharger and the throttle or if the motor is intercooled, between the intercooler and the throttle.

Greg
 

·
Registered
Joined
·
625 Posts
Wouldn't any standard Blow off valve work, or do you prefer the porsche one specifically?
 

·
Registered
Joined
·
400 Posts
Toby, is the idle valve 4 wire or 5 wire? The K3 only drives a 5 wire or 2 wire type. Happy to assist with the ECU installation if you have any questions, PM me.

Greg, that's interesting. I bought a turbo type BOV a while back thinking it might come in handy. It's the Bosch type that all the VW tuning types throw away and replace with shiny billet ones that don't work as well ;) I was intending putting the throttle upstream of the 'charger so I'm not clear if I'd be able to make much use of it. Your description of placing leads me to thinking you are talking about a down-stream throttle...do I have that right??
 

·
Registered
Joined
·
380 Posts
Here is a diagram from Corky Bells book I had been considering.
Keeping the throttle in the stock position certainly simplifies things and should improve throttle response.
The supercharger I have does not have a built in bypass.
With a blow off is it really needed?

TVS- cool project, my first sports car was a 68 MGB. Lot of fun but definitely a tractor motor compared to an Alfa. Do you know what the weight difference between the MG and Alfa motors is?
Can you post some pictures?
 

Attachments

·
Premium Member
Joined
·
6,243 Posts
Stand alone ecu

That would be great... sorting out the ECU might be quite a challenge in its self! I've bought a Rover KV6 alloy throttle body to use as the Rover stuff is nearly plug and play and has a throttle potentiometer and idle bypass valve built in. It also happens to be brand new and going dirt cheap on ebay!
Toby
You might check out www.sdsefi.com

The guys at Specialty Engineering put one on my Turbo Wagon three years ago.:):)
 

·
Registered
Joined
·
4,075 Posts
I use the Porsche valve specifically. It has brass internals and is superior to the other Bosch valves. It can also handle more boost before being forced off its seat. They are all about the same price so use the 993 Turbo valve.

The diagram in Bell's book has the throttle located before the supercharger. If that's the case you don't need to add a bypass valve because the supercharger's built in valve is all you need. The secondary valve is only needed with the throttle after the supercharger.

I also suggest using SDS. It's easy to program and ultra reliable. I understand Gotech is great to!

Greg Gordon,
www.hiperformancestore.com
 

·
Registered
Joined
·
26 Posts
Discussion Starter #18
Will post some pics as soon as I've past the 'wedge bits on blocks to see if they fit' stage ;)
I think using a blow off valve with a blow though throttle is probably the easiest way - but you end up wasting huge amounts of power compressing the air only to push it though a blow off valve. And consider the heating of the air! Best way would be some sort of vacuum operated dump valve - dumps all boost when the throttle is partially open. Still wast full as you're pumping the same volume of air (and with internal compression in a Roots). Also needs to be carfull you don't bend the throttle plate as in some circumstances it can have a seriously big pressure gradient acorss it when its snaped closed. I think a dump/recirculating valve with ECU control is probably the best way of making this system work as well as a draw though throttle...

A simple draw though throttle means the blower is running in a partial vacuum most of the time so uses the least amount of power - a by pass valve reduces this even further! The diagram from Corky Bell's book is what I'm aiming for - but with a air to water cooler and building it all into the inlet manifold. But this is tight on space and difficult to make!

Chris - I'll have to check on the throttle body for the number of wires... its in a box... some where!
Toby
 

·
Registered
Joined
·
400 Posts
Thanks guys. Re the ECU, Toby & I are UK based so a UK product is better for us for a number of reasons. Personally, I've been using Emerald products for about 12 years on various motors and have always been happy with the products & service. Their ECU can be mapped DIY, but that's not somehitng I've had an awful lot of success with TBH. Their new one does adaptive fuel mapping if you have a WB sensor fitted but it won't do the timing for you. WOT is easy, it's the partial throttle stuff that takes the skill IMO and that's the stuff that can make or break a car I think so I always take the car to the experts for mapping.

Greg, I didn't think I needed the BOV given I intend going for an up-stream TB but thought it wise to check, so thanks for that.

Toby, I've got a pair of charge coolers from a Jaguar XKR that I was going to use...but I may reconsider that and use one of the types that Greg uses. That being the case, I might have one or two spare cooler cores that you might be able to adapt?? PM me if you're at all interested and I'll take some pictures of them for you.
 

·
Registered
Joined
·
4,075 Posts
Guys:

I think there are a couple critical misconceptions. Here are some facts I hope will clear things up:

1. A Roots blower uses external compression. When the bypass valve is open, regardless of throttle location or bypass valve location, the blower is not compressing any air, and thus is not doing any work. Locating the throttle on the inlet side of the blower WILL NOT increase efficiency.

2. Almost all Eatons have a built in vacuum controlled bypass valve. This essentially shuts off the blower so it does not waste energy compressing air during off boost driving.

3. Regardless of the throttle position you will need a bypass valve. Take a look at all the oem applications with an Eaton blower. They all have the throttle on the inlet side, and they ALL have a bypass valve. If you locate the throttle on the discharge side, you need a SECOND bypass valve (obviously it could be set up as a blow off valve if your fuel injection system permits that).
 
1 - 20 of 41 Posts
Top