766 replies to this topic

[Thorney]

Why not buy a supercharger instead?

Simple. I actually don't believe in bolting SC's to engines that weren't designed to have them, in my experience (I'm always happy to be shown otherwise) they tend to cause so many problems long term that its not worth the development effort. I personally don't want to sell anyone elses kits for anything, everything TMS does is developed in house (with other suppliers) we won't release someone elses kits for example. I'm not criticising the SC conversion for the 2.2, sounds like they're very good with happy customers but I wouldn't do it for two reasons.

1. The NA is exactly that - normally aspirated and it doesn't matter how great a SC or any kind of FI is it will NEVER replicate the feeling of a normally aspirated car - period; there is no way on earth you can replicate that via a mechanical or exhuast gas throttle response. This means that NA cars are much easier to drive on the limit (ie on track) that FI so as such need less overall power than FI to make em quick.

2. The TB kit represents the ultimate way to get power from an NA car and retain that driveability.

and 3. (I know I said 2 reasons but this is different)

We're looking at a complete brand new engine swap complete with SC for less than £5k installed, first one is going in the Atom (for a laugh) and if it works as we expect (ie plain daft) then we'll develop it for the VX220 for release at the end of the year. IMO the TB kit will still have it beat but for those looking for FI in a VX chassis we think a complete engine swap is a better idea than bolting a charger onto an engine that wasn't actually designed to have it.

This is in no way critical of SC conversions, I know the first few kits had to be refunded due to problems but they seemed to have ironed out the issues with the Hitec kit but seeing as you can buy a GM power SC 2l engine, brand new in a crate for £3k the cost of the SC conversion seems high to me.

[Tashyboy]

Good write up Thorney but get to bed its the middle of the night. theres only me & you up & i'm at work.

[SPLAM]

1. The NA is exactly that - normally aspirated and it doesn't matter how great a SC or any kind of FI is it will NEVER replicate the feeling of a normally aspirated car - period; there is no way on earth you can replicate that via a mechanical or exhuast gas throttle response. This means that NA cars are much easier to drive on the limit (ie on track) that FI so as such need less overall power than FI to make em quick.

Have you driven a Hitec VX?

It's that I just can't believe how close to a high powered NA it feels, I don't think an NA would be 'much' easier to drive on the limit?

[Muncher]

With almost straight line RR plots, how does the supercharger conversion mean it is less driveable? When I had my Courtenay remap, the supercharger graphs were even more linear than for my NA, so surely it is even easier to drive harder?

[SPLAM]

With almost straight line RR plots, how does the supercharger conversion mean it is less driveable?

When I had my Courtenay remap, the supercharger graphs were even more linear than for my NA, so surely it is even easier to drive harder?

That's what I was getting at, will be interesting to see the TB graphs.

[MAP18W]

Why not buy a supercharger instead?

Simple. I actually don't believe in bolting SC's to engines that weren't designed to have them, in my experience (I'm always happy to be shown otherwise) they tend to cause so many problems long term that its not worth the development effort. I personally don't want to sell anyone elses kits for anything, everything TMS does is developed in house (with other suppliers) we won't release someone elses kits for example. I'm not criticising the SC conversion for the 2.2, sounds like they're very good with happy customers but I wouldn't do it for two reasons.

1. The NA is exactly that - normally aspirated and it doesn't matter how great a SC or any kind of FI is it will NEVER replicate the feeling of a normally aspirated car - period; there is no way on earth you can replicate that via a mechanical or exhuast gas throttle response. This means that NA cars are much easier to drive on the limit (ie on track) that FI so as such need less overall power than FI to make em quick.

2. The TB kit represents the ultimate way to get power from an NA car and retain that driveability.

and 3. (I know I said 2 reasons but this is different)

We're looking at a complete brand new engine swap complete with SC for less than £5k installed, first one is going in the Atom (for a laugh) and if it works as we expect (ie plain daft) then we'll develop it for the VX220 for release at the end of the year. IMO the TB kit will still have it beat but for those looking for FI in a VX chassis we think a complete engine swap is a better idea than bolting a charger onto an engine that wasn't actually designed to have it.

This is in no way critical of SC conversions, I know the first few kits had to be refunded due to problems but they seemed to have ironed out the issues with the Hitec kit but seeing as you can buy a GM power SC 2l engine, brand new in a crate for £3k the cost of the SC conversion seems high to me.

Interesting points. However..........

Whilst the 2.2 was not designed as a supercharged engine, the 2.0 supercharged engine was developed by Lotus directly from the 2.2 engine, which is why some of the components are interchangeable. If you look at the information contained in the Turbocharged drag car SAE paper (which has been mentioned on this forum many times in the past) you will see that all the 2.2 components used in the S/C conversion we offer fall inside the tested durability ratiings given in this paper. So we have no issue with the durability of this S/C conversion, which is actually more than simply a bolt on piece of kit.

When we co-developed this conversion with Hitec, the 2.0 option was both Hartmut (Hitec, who incidentally develops many of the Hartge BMW conversions and Ferrari 360 S/C conversions for Novitech Rosso and you cannot afford to blow up Ferrari 360 engine and they haven't) and our (Courtenay Sport) prefered option to begin with. We looked at the 2.0 S/C swap when we undertook the original brief on how to improve upon the Delta S/C kit, however cost was the main factor, but we knew with Hitec's reputation with the BMW and Ferrari tuning that developing a S/C conversion with them would not be fraught with issues.

When you look at the Stage 2 S/C conversion (240 bhp/220 lbs ft torque) we offer, a large majority of cost involved in the conversion is labour to carry out the conversion (in fact about 50% is labour) including to decompress the engine (cylinder head off) along with the additional modifications, fitting the S/C components and installing the chargecooler rad and header tank and all the associated hoses and installing the fuel ecu and moving the standard ecu.

For a straight engine transplant. the crate 2.0 S/C engine does not come with all the required components to get to this power level which we offer of 240bhp and 220 lbs ft torque. The crate engine is 205 bhp and 200 lbs ft torque, although we are led to believe by some US rolling roads that this engine produces more in standard trim (we all know about american rolling roads )

I think you'll find to get to the same reliable power/torque output with the 2.0 S/C engine you will need to carry out further modifications including decompressing the engine further to make it safe when running higher boost on aftermarket management that doesn't run knock control or other closed loop calibration that is difficult to replicate on aftermarket management. You'll need to run a smaller supercharger pulley, which involves additional cost along with fitting so increasing the power of the 2.0 S/C engine is not just a mapping issue. There is a fair degree of labour involved in removing the head to decompress it, the cost of a different S/C pulley plus fitting, also the crate engine requires the rest of the charge cooler system including the charge cooler water radiator, header tank, pump, hoses. Plus there is the cost of the aftermarket ECU and wiring harness to factor in. Also the crate engine does not come with an alternator and you cannot 2.2 alternator as the belt run is opposite so the 2.2 alternator would be spinning backwards. The 2.0 alternator is upwards of £200 or you will have to re-work the belt run and make idler pullies to change to polarity of the belt in order to use the 2.2 alternator, which would also have an additional conversion cost implication.

So with the cost of the engine, plus all the other required components to get the power to the same safe reliable output of the 2.2 Stage 2 S/C conversion, plus the cost of the labour involved to fit the 2.0 engine into the 2.2 car you will find that it is more expensive than the conversion we offer.

Furthermore we had a 2.0 S/C engine on order recently with GM in America, for a customer who had a blown 2.2 lump and in January this year GM America realigned this engine price which meant it went up by a further £893 inc VAT so the chances of now getting a crate engine for 3k from a legitimate warranted source are slim to non existant.

I agree that the 2.2 is a normally aspirated car however that doesn't mean to say the S/C conversion detracts from that, but as a VXT owner and having driven S/C cars regularly it is fair to say that the 2.2 S/C still offers the driveability of the N/A car and it is an easier car to drive than a VXT as it does not have the huge wallop of torque that the VXT has and as such is arguably an easier car to deliver the increased power as it is very linear in its delivery.

As for TB's being the ultimate way to get power, yes if you do not want to go to any form of forced induction, however I have yet to see a set of throttle bodies increase power on an engine by 95 bhp to get to the level of performance of a S/C car or achieve a cylinder fill equivalent to 11psi of boost pressure required to deliver 219 lbs ft of torque at 2,500 rpm, but I await with interest the results and am happy to be shown otherwise

[lotusbeater]

Only a few personal observations Throttle bodies, I'd buy them for the sound they produce and looks straight away S/C, haven't driven a VX with S/C but on other cars that I've driven with a S/C I love the low down grunt Turbos, the feeling of all that power when you're on full boost can be nothing short of breath taking The one thing I'm glad of is that there's so many different ways to tune cars, even one like ours that you rarely see on the roads. Everyone will have different opinions on which is best, and what will suit their driving style/budget/use of the car I guess that someone now will post a load of graphs and other evidence ? that proves that their car is the best

[Dibba]

Agree entirely with Lotusbeater - summed up very nicely I think the cliche of "variety is the spice of life" comes into play well here. The VX is a great car and to then have further varied options of tuning is a huge bonus and there is surely room for all ? The most important thing is that the choice is there for people as we will all have different preferences, priorities, budgets etc This forum is excellent at providing information on those choices and it is important that the real data and facts are maintained in an open and constructive fashion, otherwise we will run the risk of degenerating to the type of sometimes less than helpful "banter" that can be seen on some Lotus forums regarding engine options ! I had my NA converted to S/C by Courtenay's and love it to bits, not cheap, but the quality of installation and service was simply excellent. Equally I can see the attraction of a NA with TB's and also the power achieved on some of the turbo cars is mindblowing ! At the end of the day it's all about having some fun and it would be boring if we all had the same Just my 2p

[snoopstah]

I guess the thing that concerns me (someone about as non-technical as they get) is how a throttle body conversion can be as reliable as a supercharger conversion. Getting 240bhp out of a supercharged 2.2 engine is good, but hardly pushing the limits of engine technology - it's around the same bhp/litre as a standard Mini Cooper S. However, getting 220bhp (which I believe is the sort of power that is being talked about) out of a 2.2 litre NA engine is the sort of figure which Japanese car manufacturers can do reliably, but nobody else seems to be able to manage. 100bhp/litre NA engines are still pretty rare... But as said at the beginning, I know less than nothing about this.

[markv]

1. The NA is exactly that - normally aspirated and it doesn't matter how great a SC or any kind of FI is it will NEVER replicate the feeling of a normally aspirated car - period; there is no way on earth you can replicate that via a mechanical or exhuast gas throttle response. This means that NA cars are much easier to drive on the limit (ie on track) that FI so as such need less overall power than FI to make em quick.

Have you driven a Hitec VX?

It's that I just can't believe how close to a high powered NA it feels, I don't think an NA would be 'much' easier to drive on the limit?

I've driven a Hitec Speedster. Allthough it was a short run, I was very well able to spot the difference in engine reaction on throttle. It IS different from an NA. Don't get me wrong, it has LOADS of torque and power, but it is a different reaction to the throttle then my NA.

And in the trim my NA is in (allmost standard) it is VERY sluggish in reaction. Still, I would prefer the way it reacts to a compressor. Allthough I would love the same power.

I'm sure that with a REAL remap, like the one that should be possible with the new ECU John is going to use, and some other tweaks, the difference in reaction will be much more emphasized between a compressor and an NA.

But it all comes down to a matter of taste, as is will all the things you change on a car. With the VX/Speedster it's even more obvious, so many people, so many ideas...

Personally can't wait for the TB details

Mark

[markv]

BTW, on the reliability part. I guess with tuned engines that run under forced induction, it is trickier to get them as reliable as a tuned NA. The effects of running the engine lean under forced induction are much worse than with NA, which is a frequent killer with engines I've seen.. The downside of getting more power out of an NA is usually running more revs. More revs are usually ok up to a point (most that I've seen take 7200 without problems). If you go higher you usually need to make some changes, or the reliability of the engine will go down. If John gets the power from the NA without gonig over the 7200, I would guess that a NA TB setup will be more reliable then a compressor setup. If I have understood correctly the compressor uses an add-on computer besides the standard ECU to get things running correctly. Personnly I don't like that. Without knowing all the details, it sounds like a workaround for some problem running the car with only the standaard ECU. Judging from the GM documentation on the compressor add-on for the 2.2 it isn't needed, they remap (or maybe use new software) to run the compressor with the standard ECU. Then again, I guess the 2.2 is pretty strong, so I don't know if you really will notice the difference. Only one way to find out, try it Mark

[Arno]

Just drop in a Honda K20.. Problem solved! Bye, Arno.

[cxs]

Hello, Just to point out some important aspect regading the concept of comparing the NA with the SC. Independently of the Torque curve ( that has a direct relation with power regarding the rev value ), there is a point that should be measured precisely to identify a engine "soul" And here you would see the diference between a NA and any SC or TB engine. Imagine that for a given rpm Value ( call it rpm) we make a scale of 50 point in the voltage range of the throtle pad. Then stabilize the engine at each thortle voltage input, and the measure the engine increase of torque for small changes of increase of voltage in the pad. This would be similar to keeping the foot still, and then accelerating a little more. The reaction of the engine along these 50 points ( for a given time reaciton measurement) would give a nice 2D graphic for that rpm value. Now, extend that 2D graphic in all the rpm range, making a 3D surface. This would have no power measurement, just the "foot-engine-torque" relatinship... This would a very nice way to really compare engine behaviour. I guess you would never get a much linear and resposive chart as the NA one. One reason for SC linearity charts for torque along the revs is that the test is done full throtle, and so it hides this small detail, that can really be seen with this kind of graphics or by simply driving the car day by day. By the way, in high speed curves, where oyu are already in the limits, specially with high power cars, this behaviour is really needed, orelse you risk much more over steering. Even with this said, I still consider the HITEC kit. But I would love to know more about the TB kit.... Anyone heard about detuned group A engines for road usage? Someone told me about this, that could be used, but kind of expensive... Anyone wants to post his experiences in the day to day driving of HITEC kits? Cheers...

[SPLAM]

1. The NA is exactly that - normally aspirated and it doesn't matter how great a SC or any kind of FI is it will NEVER replicate the feeling of a normally aspirated car - period; there is no way on earth you can replicate that via a mechanical or exhuast gas throttle response. This means that NA cars are much easier to drive on the limit (ie on track) that FI so as such need less overall power than FI to make em quick.

Have you driven a Hitec VX?

It's that I just can't believe how close to a high powered NA it feels, I don't think an NA would be 'much' easier to drive on the limit?

I've driven a Hitec Speedster. Allthough it was a short run, I was very well able to spot the difference in engine reaction on throttle. It IS different from an NA. Don't get me wrong, it has LOADS of torque and power, but it is a different reaction to the throttle then my NA.

And in the trim my NA is in (allmost standard) it is VERY sluggish in reaction. Still, I would prefer the way it reacts to a compressor. Allthough I would love the same power.

Not quite sure what you are saying, you say it's different but you don't say what is different. I suppose if you are going to nit pick then at low revs below 1500 and the throttle is floored then yes their is a VERY slight hesitation before pick up, but these revs would never be used on track or when pushing on on the road.

Don't get me wrong though variety is deffo the spice of life and I don't think anybody has argued with that.

All the tuners deserve a lot of credit.

[SPLAM]

Anyone wants to post his experiences in the day to day driving of HITEC kits?

Cheers...

OK here goes...





..awesome, not really a lot more to say, sorry.

[Dibba]

Just drop in a Honda K20.. Problem solved!       

Bye, Arno.

Ahhh yes - - all those lovely screaming revs !! - but then you would still face the same dilema - futher upgrade = throttle bodies vs. supercharger !!!!!!

[SteV6]

EGI from the German Forum has done a Honda-swap with help from Komo-Tec. Not the cheapest way of tuning a VX220 though SteV6

[MAP18W]

BTW, on the reliability part. I guess with tuned engines that run under forced induction, it is trickier to get them as reliable as a tuned NA. The effects of running the engine lean under forced induction are much worse than with NA, which is a frequent killer with engines I've seen..
The downside of getting more power out of an NA is usually running more revs. More revs are usually ok up to a point (most that I've seen take 7200 without problems). If you go higher you usually need to make some changes, or the reliability of the engine will go down.

If John gets the power from the NA without gonig over the 7200, I would guess that a NA TB setup will be more reliable then a compressor setup. If I have understood correctly the compressor uses an add-on computer besides the standard ECU to get things running correctly. Personnly I don't like that. Without knowing all the details, it sounds like a workaround for some problem running the car with only the standaard ECU. Judging from the GM documentation on the compressor add-on for the 2.2 it isn't needed, they remap (or maybe use new software) to run the compressor with the standard ECU.

Then again, I guess the 2.2 is pretty strong, so I don't know if you really will notice the difference. Only one way to find out, try it

Mark

You're right in that running an engine lean can cause damage, however the S/C conversion does not run lean, due to the on boost fuelling. Retaining the standard ecu on the S/C conversion retaines all the safety functions built in by the manufactuer including knock control and also its ability to close the throttle to prevent internal damage should the ecu see something it really doesn't like. Between us and Hitec we have over 25 cars out there. One of which has now covered over 100,000 km. Furthermore Chris Vogler's car does nothing but spend its life around Hockenheim and the Ring with no durability issues.

As you say the downside of getting more power from an NA is to run more revs. This is why we rev limit the Stage 2 S/C conversion to 6,500 rpm. If you look at the power graphs you will see the engine is still making power when the rev limit is hit at 6,500 rpm, more power is available between 6,500-7000 rpm however in the interest of durability we won't let the Stage 2 rev higher than 6,500rpm, and we are making over 240bhp at this point. Paulcp has had to have a shift light fitted due to constant hitting of the rev limiter due to the speed the car get there!

The Stage 3, under development, which uses more internal component changes for further durability and reliability and will run to 7,000 rpm or so and current testing is producing in excess of 260 bhp.

Referring back to the SAE Paper on the turbocharged engine all the components are well within durability. As previously mentioned the Stage 2 S/C conversion runs to 6,500rpm specifically for durability and reliability. We will only run past 6,500 rpm on the S/C conversion with additional internal mods so that we do not compromise durability or reliability, but when we do will will again get a power increase into the bargain.

As for the piggy back ecu to control the fuelling....... Yes without a doubt it would be good to use the GM/Siemans ecu to do the whole job. However this would require a complete re-calibration of firmware and software required for bigger injectors and also to change from the 1 bar map range to run to 2 bar map range. To do the firmware change I would suggest you would either need to be GM or Siemans to be able to come up with the budget to do it. Furthermore if it were done this way it would again increase the cost of the conversion to a point where it would start to become unviable. This is why in the aftermarket nearly everywhere uses a piggy back ecu to achieve its required results. Retaining the standard ecu ensures that off boost driveability, emissions etc are as standard with the piggy back ecu controlling the signalling for the correct fuelling to meet the demands of the conversion on boost. We have been turbocharging Vauxhall engines since the early 80's, long before Vauxhall introduced a turboocharged engine into their range and have used piggy back ecu's to cope with the demands of on boost fuelling with no ill effects along with many other tuner's out there in the UK, europe and Japan.

I have to agree that TB's sound great on an NA car, and have driven many 2.0 engined cars on TB conversions. I also have to say that the S/C converted cars are fabulous in the way they deliver their power.

[PaulCP]

Hmmmmm some interesting debate here although how some can comment without having even been in an SC'd VX220 let alone driven one is beyond me. However for a real comparison between SC & TB the proof is in the pudding as they say. Only problem is we only have one half of the pudding

[clipping_point]

I hope at least some of the arguments for N/A power are correct...otherwise I´ve spent a lot of money on something completely useless

But it was fun doing it!!


Incidently:

N/A POWER RULES THE EARTH