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Supercharging CIH


moodoo
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Guys,

Am pondering about engine options for my Manta...20xe seems the obvious choice...large capacity CIH is an option, but can get expensive...then I thought about a supercharged 2.0 CIH!

I’m not looking for huge bhp, something with a nice bit of a ‘shove’ without having to rev the brains off it...supercharger running at reasonably small boost seems like a fairly ‘easy’ option...ish...🤔

Blower from a mini or some such...plenty of room on LHS of engine for fitment. Standard injection with an adjustable regulator? Or needs mapping on a proper system? 

Standard engine compression with a good head gasket, or would need a set of low compression pistons?

Has anyone here ever done it, and what was their experience?

Thanks,

Fin

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You can pretty much use everything as standard if you supercharge as your not likely to make more boost that 7psi anyway, the real bonus been over coming the restriction the CIH suffers at the upper rev range. 
LE Jetronic would be able to handle it too with a Rising Rate FPR.

The only 1 thing I would change from std is ignition, move to mappable. And if your going that far, then you could  spend a little more and change it for a full ECU to handle it all. TPS would need to be changed on throttle body,  add manifold pressure sensor (some have these already built in to ecu, such as Mega Squirt2) and crank sensor (front crank pulley from 2.4 etc or get a trigger wheel from eBay etc.

This method means no restrictive Air metering, you can add Closed loop Lambda as option and it can be fully mapped to some slightly larger injectors. 
Ignition would be wasted Spark (2 coil ford type etc) and none sequential injection, and it will handle the high n/a CR. One good thing about high Ethanol fuels is they are better to keep away from detonation 😎
 

A very quick rule of thumb would be 5-6% per PSI of boost if you can keep within thermal parameters (intercooler`). So 7PSI

110BHP/100 = 1.1 x 6 = (round up for laziness) 7BHP per PSI. x 7 (the boost) +49BHP  So around 160BHP, but a far better torque profile.

This us why Turbo Charging is usually preferred as easier to creat bigger boost pressures, at the cost of lag

 


 

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1 hour ago, cam.in.head said:

a 2.2 through a 3.67 axle gives a hell of a  noticeable increase (to me) and leaves it relativaly standard and reliable. obviously 2.4 would be even better !

To use the torque properly you should be going 3.44 though, for longer gears.

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Right now I have a 2.2, on 2.0 LE injection. It’s no rocket ship, but it’s fine. If I were to go 2.4, I don’t know if I’d really notice much of a difference?

I have a spare ported 2.2 head, so I’d build a new engine rather than mod what I have. I’d need a new crank, pistons, rods, basically a 2.4 bottom end, which mightn’t be easy to find, or cheap? I’d need more fuel in it, changing the fpr to give me more pressure would be a much cheaper route than going full mappable Ecu, although Probably pointless trying to run a 2.4 that way, you’d have to go for a proper ecu...and maybe throttle bodies? I guess you could run the engine on a proper ecu with the standard manifold??

Alternative is to build a 2.0, and supercharge it. Building a 2.0 bottom end will be more straightforward in terms of parts availability.

Going full mappable ecu gets expensive by the time you get someone to map it,  assuming you can get someone good. Plenty of guys here who will ‘have a go’, but getting someone who knows what they’re at is a different thing. 

At 6 or 7 psi, would I need lower compression pistons, or standard would be ok you think?

Any idea what final drive am I likely to have in my 1.9 (a series) axle?

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i suppose it depends on what you want or are used to. my 2.2 is totally standard and on 2.2injection and 3.67 diff  also ive changed to auto but mine is very powerfull. changes to top fairly soon and goes up hills like they were not there and stays in top. fast enough for me !

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2 hours ago, Nivlek2525 said:

Following this.

Could you use a thicker gasket and a 2.2 or 2.4 head to get the compression down a little if it was needed?

At 6-7psi if you reduce CR you will just lose power. It really is not needed as the boost comes mostly in a rev range when the dynamic CR starts to drop off due to poor cylinder filling. Even at 6-7psi, you should consider head work so that it optimising cylinder filling, boost does not overcome a poor flowing head completely, so further gains to be made. 

As I said in the first line of my post above, the standard LE-Jetronic will be able to cope with this with just a Rising rate Fuel pressure regulator changed to help you get a more correct fuel rail pressure during the slight boost conditions. It will struggle past this lever though and you can consider it at its limit as such.

To just explain about CR,  modern Turbo engines still run fairly high numbers, this is to help low end torque and they allow the ignition to handle the high boost. Low end torque is of more benefit for drivability and acceleration. This us exactly why modern EV cars are great off the line as they develop nearly 100% torque at 1rpm and remains fair constant only dropping as the motors max bhp is achieved.  
This is why you should perhaps not write off that 2.4 conversion. The bottom end torque is very good and you will notice it during acceleration. 
 

 

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1 hour ago, Jessopia74 said:

At 6-7psi if you reduce CR you will just lose power. It really is not needed as the boost comes mostly in a rev range when the dynamic CR starts to drop off due to poor cylinder filling. Even at 6-7psi, you should consider head work so that it optimising cylinder filling, boost does not overcome a poor flowing head completely, so further gains to be made. 

As I said in the first line of my post above, the standard LE-Jetronic will be able to cope with this with just a Rising rate Fuel pressure regulator changed to help you get a more correct fuel rail pressure during the slight boost conditions. It will struggle past this lever though and you can consider it at its limit as such.

To just explain about CR,  modern Turbo engines still run fairly high numbers, this is to help low end torque and they allow the ignition to handle the high boost. Low end torque is of more benefit for drivability and acceleration. This us exactly why modern EV cars are great off the line as they develop nearly 100% torque at 1rpm and remains fair constant only dropping as the motors max bhp is achieved.  
This is why you should perhaps not write off that 2.4 conversion. The bottom end torque is very good and you will notice it during acceleration. 
 

 

Cheers Jess. 

I find this stuff really interesting. I've not given up on a 2.4 just yet. All options are in the table but a supercharger is an interesting option...

Engine on hold while I focus on bodywork.  It's taking an absolute age to sort out. All panels are epoxy primed now and most of the car is in 2k high build.  I'll update the thread soon....

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21 minutes ago, Nivlek2525 said:

Cheers Jess. 

I find this stuff really interesting. I've not given up on a 2.4 just yet. All options are in the table but a supercharger is an interesting option...

Engine on hold while I focus on bodywork.  It's taking an absolute age to sort out. All panels are epoxy primed now and most of the car is in 2k high build.  I'll update the thread soon....

We’ll I think a Supercharged CIH 2.4 woukd be very interesting 😎

OR, how about a SC straight 6 AJ16 engine from a Jag lol I love the sound of my jags SC when it comes up to speed, very cool. Needs restoring and not really started yet as been collecting parts for the last 5 years.  ( pic is not my car btw), but the SC off the Jag would be too big for a 2.4. An EATON M65  from a Merc SLK 230 Komoressor would be a nice match indeed 🤔😎

52ED340C-6764-4877-85C3-7D09081DFD6D.jpeg

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2 hours ago, Jessopia74 said:

At 6-7psi if you reduce CR you will just lose power. It really is not needed as the boost comes mostly in a rev range when the dynamic CR starts to drop off due to poor cylinder filling. Even at 6-7psi, you should consider head work so that it optimising cylinder filling, boost does not overcome a poor flowing head completely, so further gains to be made. 

As I said in the first line of my post above, the standard LE-Jetronic will be able to cope with this with just a Rising rate Fuel pressure regulator changed to help you get a more correct fuel rail pressure during the slight boost conditions. It will struggle past this lever though and you can consider it at its limit as such.

To just explain about CR,  modern Turbo engines still run fairly high numbers, this is to help low end torque and they allow the ignition to handle the high boost. Low end torque is of more benefit for drivability and acceleration. This us exactly why modern EV cars are great off the line as they develop nearly 100% torque at 1rpm and remains fair constant only dropping as the motors max bhp is achieved.  
This is why you should perhaps not write off that 2.4 conversion. The bottom end torque is very good and you will notice it during acceleration. 
 

 

Jess, it certainly is pretty good off the line, especially in a nice light A series 🙂

59 minutes ago, Nivlek2525 said:

Cheers Jess. 

I find this stuff really interesting. I've not given up on a 2.4 just yet. All options are in the table but a supercharger is an interesting option...

Engine on hold while I focus on bodywork.  It's taking an absolute age to sort out. All panels are epoxy primed now and most of the car is in 2k high build.  I'll update the thread soon....

If you do go with the 2.4 just shout if you need any advice before you start the build. Pistons and cam are the things to get right on the 2.4!

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Thanks a lot for the input guys. Food for thought.

I wouldn’t consider my 2.2 particularly fast, it is nice and torquey up hills alright, but then I built it myself, it’s never been near a rolling road, so maybe I made a bags of it!!

You have full mappable ecu and throttle bodies on your 2.4, right Andy? Any less costly options for fueling a 2.4? Standard manifold with ecu?  Le jetronic with different fuel pressure reg?

I think building a decent 2.0, with a supercharger, is likely to be a fairly economical route to a nice ‘fast road’ engine, at least in my head! If it worked out ok, I can always add proper injection and TBs at a later date.

I need to measure the cc of the chamber in the 2.2 head I have to see where CR would end up. Its got I think 46mm inlets, not sure on exhausts.

mind you...as my project is a standard rolling shell at the minute, I won’t be needing an engine any time soon!!

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37 minutes ago, moodoo said:

Thanks a lot for the input guys. Food for thought.

I wouldn’t consider my 2.2 particularly fast, it is nice and torquey up hills alright, but then I built it myself, it’s never been near a rolling road, so maybe I made a bags of it!!

You have full mappable ecu and throttle bodies on your 2.4, right Andy? Any less costly options for fueling a 2.4? Standard manifold with ecu?  Le jetronic with different fuel pressure reg?

I think building a decent 2.0, with a supercharger, is likely to be a fairly economical route to a nice ‘fast road’ engine, at least in my head! If it worked out ok, I can always add proper injection and TBs at a later date.

I need to measure the cc of the chamber in the 2.2 head I have to see where CR would end up. Its got I think 46mm inlets, not sure on exhausts.

mind you...as my project is a standard rolling shell at the minute, I won’t be needing an engine any time soon!!

Yep, Fin

Running the fully mappable Omex 600 ECU on throttle bodies. I decided on that route as the twin carbs on the 2.1 was nice but you could never get it completely setup for the full rev range, there was always a compromise, but not with the Omex. The actual Omex system is not too bad and i recon you could get a second hand set of throttle bodies to keep the cost down, the expensive bit is getting it setup!!

I dont know the full power of mine as i got it initially setup be fore the world went to pot 🙂 got to get back and have the full power run when i can.

What do you think you will be looking at cost wise to do the super charger route?

 

Andy

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Supercharger itself is fairly cheap second hand...I can do any cad work needed for mounting it and routing air...also have a few suppliers in work who could do any fabrication needed at good rates...then it’s a new fuel pressure regulator, plus supercharger bypass valve, etc...mappable ignition setup, map sensor, tps...maybe a new set of 2.0 pistons or a decent bottom end if I could get one. Need engine bearings, seals etc, but nothing mega money.

Like you say, getting the thing mapped, even just the ignition, may be the single biggest expense.

Better never to total these things up too much in advance...save scaring yourself...you know how man maths go! If I got that lot screwed together and going ok, I can always upgrade TBs and injection later. 

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Have you seen the guys in Sweden with superchargers fitted. One guy had 400bhp plus out of a 8v cih engine. Twin v belts slipping so changed to tooth belt. Granted the engine is no where near standard any where. There was some write ups on opel tuners years ago maybe find those.  Looked into this year's ago using a volumex charger off a lancia. Never got further than planning stage. No real after market ecu available in mid 80s. 

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1 hour ago, rutts said:

Have you seen the guys in Sweden with superchargers fitted. One guy had 400bhp plus out of a 8v cih engine. Twin v belts slipping so changed to tooth belt. Granted the engine is no where near standard any where. There was some write ups on opel tuners years ago maybe find those.  Looked into this year's ago using a volumex charger off a lancia. Never got further than planning stage. No real after market ecu available in mid 80s. 

Definitely achievable with big boost and a diesel crank/2.5l capacity. Would be looking at 15-18psi of boost.

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Possibly worth looking on the mx5 supercharged forums/Facebook pages. 

Lots of information. Engines are of a similar vintage. Ecu and injection system is similarly not mappable. 1.6 mx5 injection system looks almost the same as the manta one. 

I have an eunos roadster and my understanding is the internals are bullet proof which may not be the case for a stock CIH but there's bound to be lots of transferable information.

Just a thought.

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1 hour ago, Nivlek2525 said:

Possibly worth looking on the mx5 supercharged forums/Facebook pages. 

Lots of information. Engines are of a similar vintage. Ecu and injection system is similarly not mappable. 1.6 mx5 injection system looks almost the same as the manta one. 

I have an eunos roadster and my understanding is the internals are bullet proof which may not be the case for a stock CIH but there's bound to be lots of transferable information.

Just a thought.

I bought a crappy MX5 just for track days but have used it as a daily driver for 8 years and it’s still going strong. I looked at supercharger options for it a while back and the M45? Mini charger, as mentioned earlier in the stream, popped up time and time again. I think it would look great on a Manta but it may be a lot of work for an unknown increase in performance. Possibly quite a bit cheaper than some other options discussed.

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3 hours ago, Nivlek2525 said:

Possibly worth looking on the mx5 supercharged forums/Facebook pages. 

Lots of information. Engines are of a similar vintage. Ecu and injection system is similarly not mappable. 1.6 mx5 injection system looks almost the same as the manta one. 

I have an eunos roadster and my understanding is the internals are bullet proof which may not be the case for a stock CIH but there's bound to be lots of transferable information.

Just a thought.

It’s far more advanced than the LE-Jetronic on the Manta. Closer to the very late c20xe coil pack Motronic 2.8 for function, just a flap type AFM rather then Hotwire.

 

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Yeh, I've had a quick run through some of the MX5 forums, as you say there seems to be a fair bit of info there on supercharging with that M45 Mini unit. Haven't gone into it in huge depth yet, but seems to be enough people that have done it successfully to make me think it could be doable.

 
There was also mention of supercharger units with an electric clutch, such that the blower could be set to be engaged only above a certain throttle opening, thereby eliminating any drag at idle/coast. More standard approach is a bypass valve driven by vacuum off the inlet manifold. 

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5 hours ago, moodoo said:

Yeh, I've had a quick run through some of the MX5 forums, as you say there seems to be a fair bit of info there on supercharging with that M45 Mini unit. Haven't gone into it in huge depth yet, but seems to be enough people that have done it successfully to make me think it could be doable.

 
There was also mention of supercharger units with an electric clutch, such that the blower could be set to be engaged only above a certain throttle opening, thereby eliminating any drag at idle/coast. More standard approach is a bypass valve driven by vacuum off the inlet manifold. 

Indeed, been about for a long time. Remember those mad max films with a switch to enable the supercharger!  It’s basically a way to completely disengage it for economy reasons, a bit like the clutch on the AC units. In practice a bypass is more than enough for reliably service life, otherwise you would have seen more of these applications as OEM application.

In practice it would not be based on throttle position as such as you can get to 50% open throttle, but low power demands as such. Remember the Supercharger (in most applications we are talking about in this thread) us a fixed volume ,gulping, unit per rpm and hence why it has efficiency drop off as it’s rpm drop off (fill time reducing just as with the engine cylinder). It’s inversely the Exhuast turbo becomes more efficient the larger the compressor size and higher rpm generatoring more still rapidly expanding gasses going into the exhaust ports at higher rpm.

Best of both worlds was utilised by some manufacturers  using Supercharger and Turbo (along with charge cooling might I add). 😎 very cool if you fancy it lol

 

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21 minutes ago, Jessopia74 said:

Best of both worlds was utilised by some manufacturers  using Supercharger and Turbo (along with charge cooling might I add). 😎 very cool if you fancy it lol

Lancia 037 anyone?! Now you’re talking!

I agree that the bypass option would be the way to go for simplicity. In theory you could play around with the spring rate in the bypass valve to tune at what stage the blower kicked in, right?

If you were doing the electric clutch version, what would you use to properly control the activation point? Something that was set to come in at only Full, or nearly full, throttle would work, no? You’d never be in a situation with the throttle wide open, but not wanting the extra power?

 

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15 minutes ago, moodoo said:

Lancia 037 anyone?! Now you’re talking!

I agree that the bypass option would be the way to go for simplicity. In theory you could play around with the spring rate in the bypass valve to tune at what stage the blower kicked in, right?

If you were doing the electric clutch version, what would you use to properly control the activation point? Something that was set to come in at only Full, or nearly full, throttle would work, no? You’d never be in a situation with the throttle wide open, but not wanting the extra power?

 

You want it low down the better, but obviously it’s a balance between power requirements to spin it, so your likely talking about an oversize type setup, like 2x capacity+ Per Rev. In that instance, it would be around the 2000rpm mark when the engine is developing enough torque to spin it efficiently. Can’t recall any setup along these lines unless talking about the vari-drive centrifugal compressor wheel type ( belt driven turbo compressor housing). https://www.rotrexshop.com/rotrex-superchargers/

I think just a permanent drive Eaton would be ample, get that working then worry about improvements 😎 

 

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31 minutes ago, Jessopia74 said:

I think just a permanent drive Eaton would be ample, get that working then worry about improvements 😎

Yeh you’re right...just hard to stop the mind wandering to revision 7 before I’ve even bought a single screw for version 0!

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22 minutes ago, moodoo said:

Yeh you’re right...just hard to stop the mind wandering to revision 7 before I’ve even bought a single screw for version 0!

Nothing wrong planning 😎

Dont forget you can also charge through a carb, but the std injection plenum would be a better choice. BMW did use a version of LE - Jetronic that had fuel trimming from a looped Lamda, but a rising Rate Fuel pressure regulator would be adequate.

The mini one does look a good option for getting started. V-ribbed belts are fitted to the 24v lump and 2.4ne engines that should be able to have pulleys transferred over.

Some good pictures of the mini charger layout https://x8r.co.uk/over/mini.html 

Need custom inlet and outlets making up, but plenty of room on the N/S for relocating the AFM and pipe work to an intercooler 

 

Edited by Jessopia74
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