Peter Cobbold Posted December 31, 2014 Report Share Posted December 31, 2014 Steve, I'm not at all familiar with EFI. On the face of it, fitting six injectors into the runners doesnt look impossible, but there will always be unexpected snags.This book covers EFI modifications for superchargers: http://www.amazon.co.uk/Supercharged-Installation-Supercharger-Engineering-Performance/dp/0837601681/ref=sr_1_2?ie=UTF8&qid=1420023640&sr=8-2&keywords=corky+bell Peter Quote Link to post Share on other sites
TriumphV8 Posted December 31, 2014 Report Share Posted December 31, 2014 Another recommendation: http://www.amazon.co.uk/Performance-Fuel-Injection-Systems-HP1557-ebook/dp/B003QMLC5Q/ref=sr_1_2?ie=UTF8&qid=1420025533&sr=8-2&keywords=megasquirt It is from the owners of DIY-Autotune where the Megasquirt can be bought but covers a lot of other systems on the market. Do not know what type of EFI is in use, Megasquirt for example can handle pressure up to 1.5 bar without additional effort if you are on speed-density setup. Quote Link to post Share on other sites
Peter Cobbold Posted December 31, 2014 Report Share Posted December 31, 2014 Good morning Peter, Thanks for your comments. I have EFI fitted at the moment and I am feeling a bit reluctant to ditch it all for a carb set-up. I have a new cam and was going to get some head work done so for a modest outlay I reckoned I could get a satisfactory increase in performance. But then I got the SC bug and I've been trying to justify the extra cost. I agree with you that the Moss kit is the sensible way to go however, I thought that I would explore the alternatives but like you say bespoke engineering solutions do tend to cost more that one anticipates. Thanks Steve Steve, There's a real s/c guru near you: http://www.jagweb.com/aj6eng/supercharging_article.php ( address at end of article) A famous name in drag racing circles: http://www.britishdragracinghof.co.uk/members/dennis-priddle He was racing Top Fuel in early '70s so getting on a bit now.... Peter Quote Link to post Share on other sites
John Jervis Posted January 12, 2015 Report Share Posted January 12, 2015 I have more or less finished installing the Moss kit. It is straight forward, easier than the instructions suggest as they are written for a left hand drive car, so there are parts that are left over as not needed. Hopefully I will start the engine in a week or so time permitting. Removal of the PI system is easy. I have installed and plumbed in a new larger alloy tank and new fuel lines. Because of the extra heat I have the AFR sensor by the gearbox behind the bell housing, this is just past where the down pipes connect with the single large bore exhaust pipe. This also allows the wiring from the sensor to the gauge to run straight into the car via the transmission tunnel like the O/D wires away from any heat source. There have been no problems with the installation and it is clear Moss have tested to death to make sure anyone with a bit of sense can fit it. Whether it will actually perform as it is we shall see. As Peter says there is plenty of scope for improvement should I wish to do it, which I do. GTT raises some useful points about cams and head work as we know so again that is another avenue to follow. I think it really depends on if you want a plug and play installation, or are really interested at an amateur level in how things work, how things can be improved, and you have the time and money to do it. Quote Link to post Share on other sites
Barry911 Posted January 12, 2015 Report Share Posted January 12, 2015 Sorry, a silly question then John, is yours a RHD? Quote Link to post Share on other sites
Peter Cobbold Posted January 12, 2015 Report Share Posted January 12, 2015 (edited) John Am rather envious of the ease of fitting compared with home-build ! The UEGO AFR sensor measure tiny levels of oxygen so make absolutely sure the upstream exhaust pipe join is gas-tight. Otherwise you coul get spuriously lean readings. Yes lots of future possibilities ..... Peter PS You want me to post your record of the work on my blog or you going to do your own blog ? Edited January 12, 2015 by Peter Cobbold Quote Link to post Share on other sites
Tim D. Posted January 12, 2015 Report Share Posted January 12, 2015 Good to know it is straight forward. Have ordered kit for mine. Will have the low compression head and higher boost hopefully. I notice that moss US are now offering a heat shield to put between the blower and exhaust. Have also used an afr for years. As the exhaust is off I may fit a sensor boss in case I want to wire one in permanently. Pictures of the install would be great. Cheers Tim Quote Link to post Share on other sites
John Jervis Posted January 12, 2015 Report Share Posted January 12, 2015 Hi Barry, yes it is a 1972 CP UK PI right hand drive 9.5:1 CR Hi Peter, me, do my own blog???? No thanks I will send it all to you lol)))) You can do with the pictures and reports whatever you like))))) Hi Tim, I have wrapped and heat shielded the exhaust manifold, I will also wrap the cold air inlet ducting . I have bought a oval cone K&N filter that will sit in front of the grill at the front, more or less, and also some 1,5mm aluminium sheet to rebuild the radiator shroud around the cold air ducting to join back up with the rest of the aluminium shroud. Quote Link to post Share on other sites
Peter Cobbold Posted January 12, 2015 Report Share Posted January 12, 2015 Hi Peter, me, do my own blog???? No thanks I will send it all to you lol)))) You can do with the pictures and reports whatever you like))))) John, Agree ! - I nearly gave up, steep learning curve.. Email me the bumpf and I'll do the rest... Peter Quote Link to post Share on other sites
Tim D. Posted January 12, 2015 Report Share Posted January 12, 2015 I use Google's Blogger. As easy as writing on the forum. Do you have a picture of the cold air duct? Tim Quote Link to post Share on other sites
Steve P Posted January 12, 2015 Author Report Share Posted January 12, 2015 Good evening gents, Peter, Tim & John are using low 7.5cr and 9.5cr heads respectively. The answer to this question probably lies within this thread but could you explain for me the effects of using a low cr vs high cr head in regard to the subject matter. Thanks Steve Quote Link to post Share on other sites
Tim D. Posted January 12, 2015 Report Share Posted January 12, 2015 My understanding is that superchargers have the effect of increasing the effective compression ratio of the engine. As well as substantially increasing the temperature of the mixture ( unless you fit an inter cooler). If this goes too high compared to the RON rating of the petrol then you can induce detonation (uncontrolled explosive ignition of the fuel in the cylinder) in the cylwhich can make a mess of your engine ( melted Pistons etc). There is therefore a limit on the boost you can run depending upon the CR of the engine. Practically with 9.5:1 you are advised to use the standard moss kit (6psi) while 7.5:1 you can run the high boost setup (9-10psi) and perhaps more. Effect on power and torque? Bit of suck it and see. Cheers Tim Quote Link to post Share on other sites
Peter Cobbold Posted January 12, 2015 Report Share Posted January 12, 2015 (edited) Steve, As Tim says. I'll add some approximate numbers. The 7:1 low comp head allows Tim to run 9-10 psi boost without detonation , on 97RON fuel. More on detonation aka 'knock' here, its the limiting factor in si engines: http://www.autospeed.com/cms/article.html?&title=Knock-Knock-Part-1&A=110829 ( 3 parts ) The standard Moss kit delivers about 6psi whcoh is low enough to be safe from knock on 9.5 heads on 97RON fuel. It will give roughly 23% more power gain over stock by increasing the density of the intake charge. Estimates here: http://supertrarged.wordpress.com/2014/12/16/eaton-m62-blower-calculations-for-tr6/ But Tim's 9-10psi boost will gain about 35%. That looks like the gain in power is in the ratio 35 to 23. But it wont be, because the therrmal efficiency of the low compression head is about 5% less than the 9.5 head: http://www.fao.org/docrep/t0512e/T0512e0v.gif So, roughly, Tim's 'more boost with less cr' approach gains him 28/23 over the 9.5 head **. The disadvantage of low compression is the engine might feel a bit soft off-boost. But since boost comes in a fraction of a second - no turbo lag - its not a serious problem. John can retaliate with tricks to deter knock and allow a little bit more boost. Cold air intake, octane boosters, boost retard, boost enrichment, water injection. Tim can just add rather more boost, maybe shave the head a tad, and all these tricks too. We'd all be blown away by an intercooled, injected engine because inlet charge heating diminishes returns at higher boosts without intercooling. Peter ** Because if both had 9.5 heads the power ratio would be 135/123, but we have to reduce the 135 by 5% to allow for the 7:1 compression, giving 128. Edited January 13, 2015 by Peter Cobbold Quote Link to post Share on other sites
Tim D. Posted January 13, 2015 Report Share Posted January 13, 2015 As always, very eloquently put Peter. My rationale for running a 7:1 head was the following: 1) my current CP head had been skimmed so CR was the closer to 10:1 2) main aim was to keep away from detonation zone hence low CR 3) Low CR US heads are actually the least interesting for a non supercharged car and so should be cheaper. 4) If I find the CR a bit flat off boost I can always skim the head to raise CR whereas decreasing the CR of my 10:1 head is a harder technical challenge. There is also the potential to explore slightly higher boosts if I get a new pulley made. Hope this helps Tim Quote Link to post Share on other sites
Peter Cobbold Posted January 13, 2015 Report Share Posted January 13, 2015 (edited) Tim, The balance between raising Comp Rat and raising boost can be estimated. Here I've sketched out the implications of going for more boost and not skimming the head. Lots of scope for more boost with 7:1 compression. If detonation starts at effective compression of 10.5:1 then you have 3.5 ratios to fill with boost. Very roughly that would allow 13psi boost ( these are very approx; have to be mofified by experience). So is 12psi boost a feasible target. Lets put numbers on: The blower loss curve looks OK-flat up to about 10000rpm. Set that as the main limitation.** If we want to run the crank up to 5000 then we arrive at a drive ratio of 2. So that gives blower delivery of 320cfm = 9061 litres per min. Engine consumption= (2.5/2) x 0.8 x 5000 = 5000litres/min So Press Rat = 9061/5000 = 1.8 Which is 12psi boost. Density ratio = 1.45 for 62% AE Now we predict BHP at 12psi 5000rpm. Using Triumph's "125 bhp at 5500rpm" this falls 6% to correct for 7:1 compression = 118bhp The density ratio raises that to 118x 1.45 = 171 bhp. But the blower drive loss ( see blog) is about 24hp. Nett=147 bhp. If we could keep 9.5 compression and 12 psi boost we'd get (125x 1.45)-24 = 157bhp. But that would need higher octane. ** That drive loss climbs steeply at higher rpm, and boost make it steeper. However some of that lost 24hp will be recovered as the boost 'pushes on the pistons' during the inatke stroke. ie boost reduces the 'pumping loss' on the intake stroke somewhat - too tricky to estimate though ! If the VE of the blower doesnt fall off that 1.45 density ratio applies down to low rpm. I found a proper VE curve for an Eaton M90 blower - will try to refind it. The we can estimate boost every 1000rpm. Peter Edited January 13, 2015 by Peter Cobbold Quote Link to post Share on other sites
John Jervis Posted February 7, 2015 Report Share Posted February 7, 2015 Engine fired up for the first time yesterday, all seems to be working fine) I had to remove the accelerator pedal stop to get more movement as the throttle travel is very long on the Holley. Attached is a picture of the cold air duct. I made it out of a piece of sheet aluminium to join with the radiator shroud. On the other side is a K&N filter with a aluminium hose joiner through the filter inlet and sheet to give it strength. Quote Link to post Share on other sites
Peter Cobbold Posted February 7, 2015 Report Share Posted February 7, 2015 (edited) John, You'll soon be ready to point it up some hills, experience the boost. Will be very interesting to know what boost you get at various rpm, full throttle. Peter I've added that photo to your blog. https://supertrarged.wordpress.com/2015/01/19/john-jervis-fitting-a-moss-supercharger-kit/ It needs a photo of the belts runs around the crank, blower and alternator pulleys. Edited February 7, 2015 by Peter Cobbold Quote Link to post Share on other sites
John Jervis Posted February 8, 2015 Report Share Posted February 8, 2015 Not a problem Peter, I still haven't caught up with all my notes, but there are lots of pictures to come of the belt and pulleys, AFR gauge and sensor position in the exhaust etc:) Quote Link to post Share on other sites
Peter Cobbold Posted February 8, 2015 Report Share Posted February 8, 2015 Not a problem Peter, I still haven't caught up with all my notes, but there are lots of pictures to come of the belt and pulleys, AFR gauge and sensor position in the exhaust etc:) Belt and pulley photos uploaded. Quote Link to post Share on other sites
SpitFireSIX Posted July 31, 2019 Report Share Posted July 31, 2019 The power without seems ok on paper? Quote Link to post Share on other sites
sixtynine Posted August 3, 2019 Report Share Posted August 3, 2019 Rick Patton's Quote Link to post Share on other sites
Tim D. Posted August 3, 2019 Report Share Posted August 3, 2019 Mine. http://72tr6.blogspot.com/2017/ cheers tim Quote Link to post Share on other sites
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