turbo convertion of a s1
Discussion
Hi.
Have anyone tried to put a turbo on a nonturbo esprit (s1 s2) ? I know that bell & Collvil (guess i spelled that wrong ) made a "bolt on" turbo kit for the s2 before the turbo esprit was made by lotus.
But i don't think this was a real bolt on kit, but innvolved changeing pistons and carbs.
I would like to put a low compression turbo on the original engine and run it on 0,3-0,4 bar pressure which should be enough to give 190-200 hp out of the 2 litre engine. Running a regulare high modern high compression engine with up to 0,6 bar is normaly not a problem. But i don't know how this will affect the 25 year old design of the 907 engine. I know i can get the same amount of power out of the enige by N/A tuning but i would realy try the turbo ide :-)
¨
-Sverre
Have anyone tried to put a turbo on a nonturbo esprit (s1 s2) ? I know that bell & Collvil (guess i spelled that wrong ) made a "bolt on" turbo kit for the s2 before the turbo esprit was made by lotus.
But i don't think this was a real bolt on kit, but innvolved changeing pistons and carbs.
I would like to put a low compression turbo on the original engine and run it on 0,3-0,4 bar pressure which should be enough to give 190-200 hp out of the 2 litre engine. Running a regulare high modern high compression engine with up to 0,6 bar is normaly not a problem. But i don't know how this will affect the 25 year old design of the 907 engine. I know i can get the same amount of power out of the enige by N/A tuning but i would realy try the turbo ide :-)
¨
-Sverre
First of all, let me include a disclaimer:
I am not a turbo expert. There are turbo experts here.
OK, but, I have been studying up on stuff like this for the past few years, so let me tell you my observations and theories. I think that the main reason motors are so much more reliable and streetable at high power levels today than in the past is because of the electronics. My 910 motor has pretty good electronics with the GM stuff, but aftermarket today is probably much better. A good aftermarket setup is also pretty expensive.
If I was going to try to turbo a 907, and I have thought of this every time I see a running Excel go for $1200 on eBay, I would first convert it to fuel injection and use a MegaSquirt home made system to control it all. There is someone on PH with a MegaSquirt 907 now. With that, the proper sensors, and an intercooler you could probably run a good deal of boost on the stock pistons without blowing the motor.
Just my ideas and theories.
Dr.Hess
I am not a turbo expert. There are turbo experts here.
OK, but, I have been studying up on stuff like this for the past few years, so let me tell you my observations and theories. I think that the main reason motors are so much more reliable and streetable at high power levels today than in the past is because of the electronics. My 910 motor has pretty good electronics with the GM stuff, but aftermarket today is probably much better. A good aftermarket setup is also pretty expensive.
If I was going to try to turbo a 907, and I have thought of this every time I see a running Excel go for $1200 on eBay, I would first convert it to fuel injection and use a MegaSquirt home made system to control it all. There is someone on PH with a MegaSquirt 907 now. With that, the proper sensors, and an intercooler you could probably run a good deal of boost on the stock pistons without blowing the motor.
Just my ideas and theories.
Dr.Hess
I have retro fitted an aftermarket EFI system (MegaSquirt) to my 1981 S3 NA. It has many features built in for turbo applications including boost control, it is still experimental and I am not sure how far that bit has got.
I would cerainly put in the extra effort to fit EFI before going for the turbo install as the control of fueling over the carbs will make the conversion much more reliable and it also adds stuff like traction control, ignition control etc. The extra EFI bits won't cost much more than a new set of carbs which you will need anyway.
If you want more details of my EFI conversion have a look here.......www.lotusespritworld.co.uk/EModifications/Giugiaro_Fuel_Injection.html
or contact me on the email address on the LEW owners page.
As for when the revised top link chassis was introduced, it is on the 1980 factory turbos onwards and 1981 S3. It never made it onto the S2 or S2.2
Andy
I would cerainly put in the extra effort to fit EFI before going for the turbo install as the control of fueling over the carbs will make the conversion much more reliable and it also adds stuff like traction control, ignition control etc. The extra EFI bits won't cost much more than a new set of carbs which you will need anyway.
If you want more details of my EFI conversion have a look here.......www.lotusespritworld.co.uk/EModifications/Giugiaro_Fuel_Injection.html
or contact me on the email address on the LEW owners page.
As for when the revised top link chassis was introduced, it is on the 1980 factory turbos onwards and 1981 S3. It never made it onto the S2 or S2.2
Andy
Hi,
Running a turbo'd carb version isn't really a problem, except that you'll need to increase the fuel pressures to overcome the much higher plenum pressures in order that the fuel can flow, and to eliminate the possibility of lean running.
Lotus solved this in 2 ways. First they added a variable pressure fuel regulator. This is vacuum controlled and increases fuel pressures from 3.5PSI to 5.0PSI on demand. Secondly, they worked with Dellorto to produce, what was then, the first pressurized carburettor - the DHLA 45M. This was essentially a standard DHLA 45 which has replaced the standard paper gaskets with ones made of Butyl rubber. Also, turbo pressure balance tubes were installed between both carbs to maintain constant pressure in each carb, so the carb tops were recast as well.
The biggest problem you'll have are more related to the pistons. If memory serves me correctly, the CR in the early N/A cars was 9.5:1 (higher in some markets) vs 7.5:1 in the turbo cars. Using the existing pistons will cause massive detonation (or you'll have to dial down the boost so much as to make turbocharging the engine fairly moot).
Secondly, the early pistons are cast not forged. Lotus discovered in the early turbo cars that the much harsher environment created by turbocharging caused the cast pistons to crown from the intense heat. This led to a loss of compression and eventually blow-by which caused the pistons to melt (ask me how I know this). With the introduction of the '86 model, Lotus swapped the cast pistons for forged ones and this eliminated the problem. If you stay with the existing pistons, expect compression to drop at around 15k mi., with piston failure at about 30k mi. I would recommend changing the pistons for forged ones from JE or Mahle. Should cost less than $1,000USD.
All this having been said, there are several ways short of turbocharging an S1 or S2 to make power gains. This involves a more agressive cam set-up, rejetting the carbs, improving the exhaust flow and replacing the analogue ignition with a more precise electronic one (several are available). Given the concerns raised by others about the suspension and gearbox, this may be a more prudent, and cheaper path to take.
Happy Motoring! ...Jim'85TE
Running a turbo'd carb version isn't really a problem, except that you'll need to increase the fuel pressures to overcome the much higher plenum pressures in order that the fuel can flow, and to eliminate the possibility of lean running.
Lotus solved this in 2 ways. First they added a variable pressure fuel regulator. This is vacuum controlled and increases fuel pressures from 3.5PSI to 5.0PSI on demand. Secondly, they worked with Dellorto to produce, what was then, the first pressurized carburettor - the DHLA 45M. This was essentially a standard DHLA 45 which has replaced the standard paper gaskets with ones made of Butyl rubber. Also, turbo pressure balance tubes were installed between both carbs to maintain constant pressure in each carb, so the carb tops were recast as well.
The biggest problem you'll have are more related to the pistons. If memory serves me correctly, the CR in the early N/A cars was 9.5:1 (higher in some markets) vs 7.5:1 in the turbo cars. Using the existing pistons will cause massive detonation (or you'll have to dial down the boost so much as to make turbocharging the engine fairly moot).
Secondly, the early pistons are cast not forged. Lotus discovered in the early turbo cars that the much harsher environment created by turbocharging caused the cast pistons to crown from the intense heat. This led to a loss of compression and eventually blow-by which caused the pistons to melt (ask me how I know this). With the introduction of the '86 model, Lotus swapped the cast pistons for forged ones and this eliminated the problem. If you stay with the existing pistons, expect compression to drop at around 15k mi., with piston failure at about 30k mi. I would recommend changing the pistons for forged ones from JE or Mahle. Should cost less than $1,000USD.
All this having been said, there are several ways short of turbocharging an S1 or S2 to make power gains. This involves a more agressive cam set-up, rejetting the carbs, improving the exhaust flow and replacing the analogue ignition with a more precise electronic one (several are available). Given the concerns raised by others about the suspension and gearbox, this may be a more prudent, and cheaper path to take.
Happy Motoring! ...Jim'85TE
Thanks for all the replyes.
I have little doubts that the driveshafts and links will be able to handle 200 hp. Many people run 200 bhp + on normaly aspirated early esprits. even rover v8 engined ones with mutch more torque. (the driveshafts wear out anyway). But I'm rely interested in the injection convertion. This realy seems like the way to go.
I read the convertion page of David Loomes.
GREAT PAGE! I would love to hear from anyone who has more info about injection and turbo convertions.
-Sverre
I have little doubts that the driveshafts and links will be able to handle 200 hp. Many people run 200 bhp + on normaly aspirated early esprits. even rover v8 engined ones with mutch more torque. (the driveshafts wear out anyway). But I'm rely interested in the injection convertion. This realy seems like the way to go.
I read the convertion page of David Loomes.
GREAT PAGE! I would love to hear from anyone who has more info about injection and turbo convertions.
-Sverre
I have read a bit about the megasquirt and I must say it seems absolutely fantastic, as I work with computers for living and is a a big fan of freeware software projects this is a absolutely must-do.
Andy> What kind of trottle possision sensor did you use?
By the way i think I gave David credit for Andys fab page, sorry Andy.
Andy> What kind of trottle possision sensor did you use?
By the way i think I gave David credit for Andys fab page, sorry Andy.
Hi,
I was curious about this a couple of years ago. I was told by one of the Lotus specialists in the USA that many people splice the front of S1/S2 chassis' to the rear of the turbo chassis upgrading the suspension and making it easier to install the later turbo motor.
Rich Flowers
'95 S4s ...SHF63000
'79 JPS #040
I was curious about this a couple of years ago. I was told by one of the Lotus specialists in the USA that many people splice the front of S1/S2 chassis' to the rear of the turbo chassis upgrading the suspension and making it easier to install the later turbo motor.
Rich Flowers
'95 S4s ...SHF63000
'79 JPS #040
Gassing Station | Esprit | Top of Page | What's New | My Stuff