MicroSquirt.com read only forum (Jan.15,2018)

G'day Shaun
I was running two x B2 converters, and 1 x S400, 1 x S480, I never ran out of gas (single flexible line feed from tank to two converters) but I am more than sure I ran out of air! The CFM rating of GRA throttle bodies are suspect to say the least. I saw an article that stated when a S440 was flow tested it was only good for about 300CFM so choose your size carefully. One B2 is good for about 250-300HP, this more than enough for 1 x S480. I have just recently removed my setup from the car, I have had it for just on 10years and it never missed a beat but the tune ability over the rev range is not as good as GRA would have you believe (I my case anyway). With my engine I have about 45-50kpa map pressure at idle and sitting on 80-90 kph I have about 40kpa, just could never get it right across the rev range. Having said that, maybe with a stock cam things would be different? I took off the system of in search for more HP (maybe two 510 would have worked better in my application). So far even though I still haven't got my car running right (now petrol only), it certainly has a lot more power than the GRA ever had but yes I still have a big tune problem. The funny thing is I can floor mind and it doesn't miss a beat right through to 6500, cruising above 2000 seems mainly fine but below this and I have to run "stupid" afr's (<13:1) to stop it from coughing and chugging, never did that on LPG.
Anyway, back to your app, be very careful joining two vapour line outputs together. The converter relies on manifold vacuum to regulate flow and having them in parallel might (just a guess) cause one to work harder than the other. If you are worried about the B2 capacity, use one Century converter instead, these I believe have a 300-330HP rating and GRA supply them as an alternative (at a cost) but again I think your hitting a small problem with a sledge hammer! One fuel line one converter and one mixer if your wanting to run a one mixer setup.
Any, it’s late and I'm tired, good luck.

Cheers
DaveZZ

Hi davezed,

I am looking at producing 550 - 600hp out of my engine. To explain my setup further it is a 4.0Ltr OHC TFI ford engine with forced induction. So the N/A flow rate of the throttle body becomes redundant as the turbo will force air through it, which is why I have gone down the 2 converters path.

I wanted to use the MS-II for the extra inputs/outputs that it has so that it can control the thermo fans, and extra temp sensors, etc.

Cheers,

Shaun

Wow, you hair drier boys certainly get things humming! I think you need to talk to GRA, use their 1800 number as per web page. I was taught 1 converter per mixer but this obviously will not cope. Not sure if it means you will have to use two mixers or not, at $600 bucks a throw it certainly would make you think. You may also have to get a special tank with two outlets otherwise with one the hi-flow shutoff valve may become active in your case (your engine will not enjoy that). I’m pretty sure there are such item around or you may be able to get one that will allow higher flow (this is a safety feature in case of a fuel line failure). Just as a bit of food for thought, I was talking to GRA today and they have a prototype vapour injection system they are trialing at the minute. It will not be out for a year or so but sounds interesting, depends on whether you can wait or not. Like LPG-Liquid-Inject and Gas Injection Technologies, they both said mid last year they expect to have kits out by the end of last year /start of this year but still nothing has happened! I think (someone may want to correct me) but I think MS extra has more features at the minute than MS2 with respect to hair drier applications (though they are more relevant to fuel delivery). MS2 I suspect in the future will incorporate these but I don't think they are available at the moment. One tip if you go down the dual B2 converter trail (would be only marginally ok in your app), make sure you use a shutoff valve directly on each converter. These converters have a bad habit of bleeding down when you shut the engine down. What happens is your engine will flood because LPG is heavier than air and make it a pain to start. By placing a shutoff valve on the converter you reduce the amount of LPG that can bleed down through the system (remember LPG expands by up to 270 times). I originally only had the one under the bonnet on the firewall; this feed both converters, about 18 inches of flexible line from shutoff to converters. If I tried to restart the engine within an hour or so off turning it off it would take up to 10-20 seconds! After I changed this to one on each converter it would usually start within a few seconds. Another thing to take into account is ensure your vapour feed lines are as short as possible to reduce to lag, by law (I believe here in Aus) it should be less than 18 inches but shorter the better. The idea I have about using an output of MS is to power the priming solenoid. This is mainly for acceleration enrichment (but not necessary limiting it to that). GRA sell a somewhat crappy simplistic controller that vainly tries to keep you around lambda (real basic analogue circuit) that drives the priming solenoid in an attempt to achieve this, I think MS2 could do this much more accurately. Anyway it is worth a play with…
Again good luck and I hope you have strong rods/bottom end, your going to need it! Either that or a large garbage bag to put the pieces into if things go wrong. Hope you know a good dyno place also…

Cheers
DaveZZ

Hey Davezed,

The hairdryer (lol) has had alot of money spent on her. Although, the most important thing is the tune and a good dyno tuner is the single most important ingredient. I will not be starting the engines life on a MS - II system. Instead of have gone with a Haltech IG5 to get it going.

I was thinking of mounting the converters along the passenger side firewall, just above the chassis, but I see your point about the length of plumbing to the throttle body. I had thought about using liquid injection, but the technology seems fairly primative at this stage and I have heard nothing but complaints about it from people who have set it up.

Just on the lock-offs, it is now law and has been for sometime that each converter must have a lock-off and that it must be bolted to something...something about vibration shaking them loose.

To control the flow of gas from the converters If have had the converters modified so that vacuum will open/close the diaphram in the converters when boost comes on/off, a pic is attached to show what I mean.

The MS2 has alot more potential and the people around these parts seem pretty helpful with regards to problem solving. When it comes to the coding, I have no idea, but a friend of mine is a very good at this sort of thing. Actually he developes braking system technologies for motor vehicle companies.

G'day Shaun
MS2 is certainly the way of the future and the long term pluses certainly out way the short term minus. Yeh Liquid Phase started here in Adelaide back in the early /mid 90's I think and they are still yet to put out a product (think a few companies bought them out), the main problem is the expansion rate of gas under varying heat conditions. In theory it sounds great but yeah it is also like handling a time bomb, maybe one day? I ve had my system for just on 10years, back then I assume there was no law about numbers off shutoff solenoids, you live and learn... Make sure you mount the converters in the plane as shown on your picture, the diaphrams are direction sensitive and the way shown is correct. I have seen the top plate used in the fashion as shown, pretty common with Impco systems, nothing special to turbo cars, although I think you will find under vacuum it will close the diaphram and under boost open it (you probably meant that, sorry to tell you to suck eggs). With the converters, one other point, make sure they are lower than your radiator (most likely are if just above chassis) and put a air bleed fitting in the water feed line, some cars are real buggers for trapping air in the water system which will result in freezing of the converters real quick. Let me know how it works out, still have a soft spot for gas and if I could have found a few more HP with it I would have stayed with it!

Cheers
DaveZZ

More power is to be had with a LPG only setup than with a petrol only setup. Only if the engine is rebuilt to suit though. Just add a hairdryer (I love that)

Yes, that is what I meant about boost and vacuum. You knew what I meant.

I feel much more comfortable to use the MS - II because it seems to be motoring along with the developements. To begin with, once the engine runs well with the IG5, I will begin to experiment with the MS - II with enough boost to run it like an standard N/A engine with a nice cam, i.e run enough boost to bring the engines compression from 8.5:1 upto the equivelent of 9.3:1 stock engine, and see what I can do with it in terms of boost control and things, at least in that form I won't break rods or anything else (I hope), and as things prove to work, begin to increase psi and build a system that works well. I guess that's everyone objective on here isn't it???

Cheers,

Shaun.

P.S. Just as a side note, do you find the GRA boys hard to deal with...or is it just me?

Hi Shaun
If your talking about the boys in Melbourne (down south), I wouldn't feed them if I had the choice! I drive over there in desperation in an attempt to get more HP a couple years ago, spent my money and was treated like fast food, in and out in 30 minutes and the car was worse in every way, less power at top end and a real bugger to get off the line. Unfortunately they were bought out years ago as well and now are actually in Perth/Brisbane I believe, the place down south named GRA has actually nothing to do with GRA anymore (so I'm lead to believe), boy was I #&% off!!
BTW, my engine was actually built up for LPG only, I heard a lot of people say they get great performance from LPG but are yet to see it but I'm talking about N/A, I understand turbo/supercharged goes extremely well with gas.

Cheers
Dave ZZ

I 100 % agree with your thoughts with Melbourne technicians
I had nothing but misinformation and money spent.

The best I ever had my car running was going back to basics and ignoring all there advice.
I had a drivable car and after the dyno it was horrid.
I am lucky to have a very savvy friend with a v.6 twin turbo gra only 200 rear wheel kw car, just around the corner.
Back to basics and the other thing I was doing was over analysing the setup and constantly patching it, Moving balance lines.
When I started from scratch again it was much better. Still not perfect however better than any of the “Pro’s” could do.
I suppose all I can recommend is to plan and apply best practises to your setup.
And stick to the GRA recommendations not fudges that get around 1 problem but cause 2 more.
Hope this helps.
Dan.

Hey davezed,

To get the performance of the N/A LPG engine compression needs to be brought up quiet a bit 11:1ish. The octane rating on LPG is much higher ~ 106 - 120 (I have read sources that state both so I assume somewhere in between is believable).

I heard that about the Melbourne GRA as well. I bought a heap of gear of them 6 months back and they were rude and misleading in there adivce.

Shaun
Be careful about your compression ratio, I have heard people say up to 13:1 CR but what you dont hear about is how LPG loses it's octane rating at a rate of knots with heat, ie in summer here. Also the octane rating quoted is not the RON rating which I believe is the one that should be used (takes into account temperature I think, often referred to as the useable octane). I think ours can drop down to mid 95 pending on season (might be wrong). Our LPG does not have laws about the propane/butane mix, (I think US does, 99% propane), we often can have a 60/40 mix respectively which is basically crap, the only way you are going to tell is when you start leaning out, idea for a hair drier......... Before I built my engine I spoke to Shell and did a maintenance course to find out a little about things, for an old "farm engine" like mine they wouldn't recommend any more than 10:1, 10.5:1 tops. I've heard all the impressive stories but haven't seen one to date, I think its a little like rocking horse poo........ People tend to stretch the truth or fail to tell the whole story like couldn't run it in summer etc. Sorry but seeing is believing. Having said all the above I have heard a rumours that we may start getting 99% propane soon but until it is law you might find yourself in trouble one day. Ring around places like Shell etc, I found the technical guys to be very helpful. Just think of it, if it is so good why isn't every second drag car/hi po street car powered by this? Big claims have been made for the past 10years or more, but still people stay with petrol even at almost 3x the cost...



Cheers
Dave ZZ