Turbo v Supercharging

[ChimpOnGas]

Ok lets talk intercooling

More specifically, how much boost can you safely run the SC Power Rotrex setup to on a RV8 before you need an intercooler?

As I understand it all intercoolers create a restriction and the shorter the path between the compressor & the throttle butterfly the better, so an intercooler only becomes a benefit when you're producing boost over 8psi?

I know a cooler charge is always better, even on a naturally aspirated engine.

But if the intercooler is creating a restriction and you lose pressure with all that intercooler pipework, if the compressor isn't creating a lot of heat below 8psi in the first place there's an argument to say you're better off without it below that level of boost.

I'd be interested to understand this equation better.

Perhaps we've all just become so used to intercooling because turbos create more heat & are more popular, and because most forced induction vehicles are running more that 8psi of boost?

Perhaps there are some forced induction experts out there who can shed some light on when an intercooler becomes essential?

I guess wher I'm going with all this is you could install the SC Power kit in two stages, initially a lower boost 7-8psi setup without an intercooler which would be a cheaper & simpler installation.

Then when the funds have recovered & your getting complaisant with the performance, you can fit an intercooler (or an after cooler) & up the boost to 10psi with a smaller pulley.

Just thinking aloud really, what do people with experience of the SC Power like 450Nick think of this approach?

I seem to remember the first 400 SC Power fitted their kit to ran without an intercooler, and that still had a distributor & the 14CUX for heavens sake.

Surely with a stand alone ECU like my Canems I could safely get away say 7psi of boost & no cooler, kind of a cheaper & simpler step one of a two stage project project if you like?

Your thoughts on this approach

Edited by ChimpOnGas on Monday 14th October 14:34

[450Nick]

macdeb said:

Thanks Nick, thing is my heads have been skimmed and the guy who did them reckoned the comp' ratio is around 10.5:1 so I'd like to lower it and I happen to have a set of ceramic coated forged pistons that are apparently 8.0:1. I'll cc the heads then try and work out what comp' ratio I would have with new pistons. As for the cam I have a piper 285 fitted, so not suited to FI hence my questions about one. ARP studs also. One other thing, did you have the 5th gear mod done to your gearbox? Would you recommend it? I have the usual inlet mods, flared trumpets, larger throttle, enlarged and ported inlet manifold matching trumpet base and ported heads, precats replaced with non-reversal cones and ceramic coated. Also, 325mm barkes, braided, and Gaz Golds.
DAZ, my bores aren't worn, in fact they still have the honing marks in them but then it's only just clocked 17k miles from new.

Ah that makes more sense - I can see why you'd do that now. As I mentioned, Steve noticed that one of my heads had been skimmed 0.5mm, but was confident that the whole lot could be rebalanced when the heads were ported without a problem - which is going on at the moment. I would just get a blower cam when you open it up - it's the same price as an MC1 so not too bad really.

Yes I had the modified 5th gear many years ago after I lost the 5th gear circlip while cruising at 70mph back when the car was standard. I had the gearbox rebuilt and they did the mod for me automatically to prevent it happening again. I'd say leave it until it happens unless you really want to take the box out for some reason. It seems to be luck of the draw whether the circlip ever comes off and if it does, you just lose drive in 5th gear until it's rebuilt as the gear will spin on the shaft.

[Bassfiend229hp]

ChimpOnGas said:

So if you're thinking about going with the SC Power kit, best you just accept that £80 a year before you commit.

Lets be honest it's not a king's ransom is it

Think of it as "chuck in another tank of fuel a year"...

Phil

[450Nick]

ChimpOnGas said:

Ok lets talk intercooling

More specifically, how much boost can you safely run the SC Power Rotrex setup to on a RV8 before you need an intercooler?

As I understand it all intercoolers create a restriction and the shorter the path between the compressor & the throttle butterfly the better, so an intercooler only becomes a benefit when you're producing boost over 8psi?

I know a cooler charge is always better, even on a naturally aspirated engine.

But if the intercooler is creating a restriction and you lose pressure with all that intercooler pipework, if the compressor isn't creating a lot of heat below 8psi in the first place there's an argument to say you're better off without it below that level of boost.

I'd be interested to understand this equation better.

Perhaps we've all just become so used to intercooling because turbos create more heat & are more popular, and because most forced induction vehicles are running more that 8psi of boost?

Perhaps there are some forced induction experts out there who can shed some light on when an intercooler becomes essential?

I guess wher I'm going with all this is you could install the SC Power kit in two stages, initially a lower boost 7-8psi setup without an intercooler which would be a cheaper & simpler installation.

Then when the funds have recovered & your getting complaisant with the performance, you can fit an intercooler (or an after cooler) & up the boost to 10psi with a smaller pulley.

Just thinking aloud really, what do people with experience of the SC Power like 450Nick think of this approach?

I seem to remember the first 400 SC Power fitted their kit to ran without an intercooler, and that still had a distributor & the 14CUX for heavens sake.

Surely with a stand alone ECU like my Canems I could safely get away say 7psi of boost & no cooler, kind of a cheaper & simpler step one of a two stage project project if you like?

Your thoughts on this approach

Edited by ChimpOnGas on Monday 14th October 14:34

I'd speak to Colin @ SC Power about the intercooler issue. I understand they did a lot of research into when they were required, and I think the answer was: "in anything other than a boggo 4L with the standard charger setup". They took several variants on a trip right across Europe, into the Alps and hot weather and all sorts to see if any problems arose, and I think they saw some detonation potential in the bigger engines or at higher boost so recommended the intercooler for that reason. I also believe that they looked at chargecoolers as an alternative, but deemed it too complex and expensive compared to an intercooler. Again ask Colin on this one. A chargecooler would be neat and if someone specced up a decent solution then I would look at it, but I'm happy with the setup as it is and it works very well so no need to change at the moment.

Throttle response wise, yes the non-intercooled version is very slightly better, but by using TPS as reference and aggressive transient fuelling on my ECU, its all but instant anyway so it's not a problem for me.

You could definitely run the non-intercooled setup to start with, but I don't recall the delta being that much (all relative) as you need to buy a different inlet pipe for the non-intercooled version anyway which you'd have to swap out, so unless you really can't live with cutting two holes then you may as well. Even with the long inlet pipes and intercooler, it still feels very much like an NA engine.

[Bassfiend229hp]

ChimpOnGas said:

I guess wher I'm going with all this is you could install the SC Power kit in two stages, initially a lower boost 7-8psi setup without an intercooler which would be a cheaper & simpler installation.

Then when the funds have recovered & your getting complaisant with the performance, you can fit an intercooler (or an after cooler) & up the boost to 10psi with a smaller pulley.

This is the thought process that I had got to too ...

Phil

[ChimpOnGas]

450Nick said:

I'd speak to Colin @ SC Power about the intercooler issue. I understand they did a lot of research into when they were required, and I think the answer was: "in anything other than a boggo 4L with the standard charger setup". They took several variants on a trip right across Europe, into the Alps and hot weather and all sorts to see if any problems arose, and I think they saw some detonation potential in the bigger engines or at higher boost so recommended the intercooler for that reason. I also believe that they looked at chargecoolers as an alternative, but deemed it too complex and expensive compared to an intercooler. Again ask Colin on this one. A chargecooler would be neat and if someone specced up a decent solution then I would look at it, but I'm happy with the setup as it is and it works very well so no need to change at the moment.

Throttle response wise, yes the non-intercooled version is very slightly better, but by using TPS as reference and aggressive transient fuelling on my ECU, its all but instant anyway so it's not a problem for me.

You could definitely run the non-intercooled setup to start with, but I don't recall the delta being that much (all relative) as you need to buy a different inlet pipe for the non-intercooled version anyway which you'd have to swap out, so unless you really can't live with cutting two holes then you may as well. Even with the long inlet pipes and intercooler, it still feels very much like an NA engine.

Thanks for this Nick, I'll talk with Colin but here's his own words on the un-cooled 4.0 litre installation taken directly from the SC-Power website:

"The car is a pleasure to drive with boost being held to less than 6 Psi., therefore an Intercooler is not essential keeping the overall costs down. The car is achieving 270hp and 260 ft.lbs of torque at the wheels measured on the Dynamometer, this being equivalent to 320hp at the flywheel surpassing the 5.0 litre HC"

The fact I'm also running 110Ron LPG should certainly help in the fight against detonation.

Charge coolers don't need to be that complicated from what I've seen, and if you use the biggest US supplier rather than a certain UK one, the costs aren't horrendous either.

The Yanks have been putting charge coolers on blue collar V8 centrifugal supercharger projects for years now, and if you have a mid engined car a charge cooler is often your only option.

For example my mate has one on his blown Elise, so it's all well proven technology.

I did a fag packet shopping basket of everything required (& I mean everything), and it came in at £550 Sterling including shipping & taxes.

That included the heat exchanger, the charge cooler, all the pipe work, the water pump, all the pipe fittings ect ect ect, even twin fans for the heat exchanger (which is possibly overkill).

http://stores.ebay.com/Just-Intercoolers/_i.html?r...

I think we're looking at £200 (ish) more than an intercooler for the full package, but for me the benefits would be well worth it, and as we know I like to be different

The way I see it the packaging actually has the potential to be less complicated with a charge cooler.



Running the two thin flexible water pipes to & from the heat exchanger shouldn't be a massive challenge compared with the big bore rigid ally pipe work of an intercooler.

For instance you could run the water pipes within the O/S inner wing, reducing radiant heat to the charge cooler is definitely a challenge, but with one of SC-Power's manifold heat shields and some heat insulation to the unit itself the charge cooler could go here:



Tackling the installation in two phases appeals to me for a number of reasons, and in a years time when I feel the need for more power £550 for the cooler kit wouldn't seem much for all that extra go you could dial in

In the mean time I've still taken "Ol 4.0 litre Gasbag" beyond the output of a standard 5.0 litre.

Phase two gets me playing with the big kids at the strip

[fatboychim]

ChimpOnGas said:

I guess wher I'm going with all this is you could install the SC Power kit in two stages, initially a lower boost 7-8psi setup without an intercooler which would be a cheaper & simpler installation.

Then when the funds have recovered & your getting complaisant with the performance, you can fit an intercooler (or an after cooler) & up the boost to 10psi with a smaller pulley.

I did exactly that, I just bunged it on and kept the Lucas/dizzy set up then a year or two later fitted the intercooler. I did have to try a couple of different fuel regs at first though but I'm guessing your Canems will be fine with what you already have.
As Nick said, by the time you have done the initial install and then altered it and thrown away the the cross pipe the saving it may cost you a little more in the long run.

[SILICONEKID343HP]

Where does the cold water come from ? I`m wondering if air con could be used .

[ChimpOnGas]

SILICONEKID343HP said:

Where does the cold water come from ?.

The magic well near the dragon's cave

[Bassfiend229hp]

fatboychim said:

I did exactly that, I just bunged it on and kept the Lucas/dizzy set up then a year or two later fitted the intercooler. I did have to try a couple of different fuel regs at first though but I'm guessing your Canems will be fine with what you already have.
As Nick said, by the time you have done the initial install and then altered it and thrown away the the cross pipe the saving it may cost you a little more in the long run.

I think you might also need to throw in some bigger injectors pretty quickly too as mine are pretty much maxed out even without any forced induction...

Phil

[SILICONEKID343HP]

Two options ..Been told you don`t need the air box for the super charger if you have the after market ECU.

http://www.pistonheads.com/classifieds/parts-and-p...

http://www.pistonheads.com/classifieds/parts-and-p...

[Chilliman]

ChimpOnGas said:

SILICONEKID343HP said:

Where does the cold water come from ?.

The magic well near the dragon's cave

[Chilliman]

rigga said:

macdeb said:

Chilliman said:

Hey Mac did you once own a Griff

yes, two in fact!

Its not connected ...

Yes it is low mileage, never leaves the garage, same symptoms rigga Mac owns a Chim but still lives in Griff world

Typical Griff owner having breakfast thinks.......

"I wonder how much it's worth this morning"

[ChimpOnGas]

fatboychim said:

I did exactly that, I just bunged it on and kept the Lucas/dizzy set up then a year or two later fitted the intercooler. I did have to try a couple of different fuel regs at first though but I'm guessing your Canems will be fine with what you already have.

Nice Andy, how much boost did you run without a cooler?

fatboychim said:

As Nick said, by the time you have done the initial install and then altered it and thrown away the the cross pipe the saving it may cost you a little more in the long run.

But if a charge cooler could be mounted where I've indicated in my above picture, I would be keeping the cross pipe.

It a very similar idea to where the yanks fit their charge coolers on mustangs & the like, the only real difference is the blower sits on the N/S with the SC-Power Rotrex installation.

On the Yank setups the blower sits on the same side as the charge cooler, with my idea the charge cooler would be in the same place you'd still have the cross pipe becase the Rotrex sits on the N/S.









So the Rotrex would send the boost over the engine through the cross pipe to the cooler sitting above the O/S exhaust manifold between the inner wing & the O/S rocker cover, from there its just a short run to the plenum.

The in & out water pipes could run from the charge cooler within the O/S inner wing to the front mounted heat exchanger, the holes & grommets are in the inner wing already (servo pipes ect), so it should be a nice neat installation.

Just me musing an idea to help break the supercharger project into two steps (pre & post cooler), while removing the need for two holes in the nose the big intercooler pipes.

I think it would work & look quite neat, easily reversible too if you ever wanted to sell the car & the blower kit separately, which is probably the best way to maximise your return.

[fatboychim]

From memory boost was about 6psi, I've dropped a couple of pulley sizes since the intercooler and in truth I don't know what the boost is now. I just keep it safe with the A/F gauge.
I think the charge cooler sounds a good idea if you can fit it in, don't forget that the pressure relief valve is in the pipe work you are looking at replacing so that will need to be found a home and you will then have two banks of spark plugs that you can't access readily, not a big problem but something to consider.

Warning, I am now in the pub, any further posts from me may be less than helpful.

[Bassfiend229hp]

fatboychim said:

Warning, I am now in the pub, any further posts from me may be less than helpful.

[ChimpOnGas]

fatboychim said:

From memory boost was about 6psi, I've dropped a couple of pulley sizes since the intercooler and in truth I don't know what the boost is now. I just keep it safe with the A/F gauge.
I think the charge cooler sounds a good idea if you can fit it in, don't forget that the pressure relief valve is in the pipe work you are looking at replacing so that will need to be found a home and you will then have two banks of spark plugs that you can't access readily, not a big problem but something to consider.

Warning, I am now in the pub, any further posts from me may be less than helpful.

Well all the above is spot on so clearly you've not tucked into your second pint yet

6psi it is for phase one then

The charge cooler could could be lifted away fairly easily when the plugs need changing, NGK seem to think my LPG Iridium platinum chip plugs should last 50,000 miles minimum anyway.

From a quick measure up there's certainly space for one of these:



I think radiant heat soak from the O/S manifold is the biggest enemy with a charge cooler positioned between the N/S inner wing & rocker cover, but that seems the most logical place for it.

The real problem is the alternator, if you could lose it a barrel type charge cooler could take the place of the cross pipe but the alternator seems to create a high point that would make that impossible.

Enjoy the drink

[Bassfiend229hp]

...and my bloody credit card company have just upped my card limit today too ... hmmm ...

[fatboychim]

ChimpOnGas said:

I think radiant heat soak from the O/S manifold is the biggest enemy with a charge cooler positioned between the N/S inner wing & rocker cover, but that seems the most logical place for it.

The real problem is the alternator, if you could lose it a barrel type charge cooler could take the place of the cross pipe but the alternator seems to create a high point that would make that impossible.
N
Enjoy the drink

Thanks I've tucked into several, FFS it's £1.75 for a pint of Stella here!.
So heat shield over O/S manifold no big deal, I agree the alternator is very high, I have a non standard alternator on mine and I had to take the angle grinder to it plus make a mod (bend) to the cross pipe to clear the bonnet. I'm thinking you may have a little more room though what with no distributor although the hose to the swirl pot will be a problem, could the charge cooler drop in that space?

[ChimpOnGas]

fatboychim said:

Thanks I've tucked into several, FFS it's £1.75 for a pint of Stella here!.
So heat shield over O/S manifold no big deal, I agree the alternator is very high, I have a non standard alternator on mine and I had to take the angle grinder to it plus make a mod (bend) to the cross pipe to clear the bonnet. I'm thinking you may have a little more room though what with no distributor although the hose to the swirl pot will be a problem, could the charge cooler drop in that space?

Guess I'd need to relocate my coil packs for that





If it wasn't for the alternator there'd be stacks of space