Discussion
PhillipM said:
It is a problem, people just desperately want to justify why they've done it. 
Really? I've been considering a rear mount turbo for my 106 for a while. The plan was to use a length of extruded aluminium with 'fins' along the underside of the car instead of an intecooler. This would give a similar volume beween turbo and inlet as with an intercooler, and at least some of the cooling capacity.Something like this:
doogz said:
I've seen systems like this with the turbo very far back before.
Does it not induce a massive amount of lag, as there's a (comparatively) huge volume of air between the turbo and inlet manifold that needs compressed?
This is something I've tried to find out over the years as such a mod is quite popular on cars like my Camaro. Sadly I've never really found a satisfactory answer, mostly due to the age old problem of everyman and his boat getting confused between turbo lag and boost threshold. Those that do know the difference either haven't driven a rear mount turbo setup or if they have, they haven't driven a front mount setup to compare too.Does it not induce a massive amount of lag, as there's a (comparatively) huge volume of air between the turbo and inlet manifold that needs compressed?
That said, I've not yet spoken to an owner of a rear mount turbo setup who hasn't liked the end result and I've spoken to quite a few over the past 5 years or so.
Some of the theory I've garnered over the years runs along the lines of, most rear mount setup's don't run an intercooler and can achieve similar AIT's to front mount turbo setups running intercoolers.
Also the distance the turbo is from the intake manifold is not always as much as you might first think, it's just a straight run under the car and up into the engine bay. Few bends or turns.
Whereas on many front mount turbo setups, the turbo's can still be low down behind the engine, in the front bumper, ontop of the engine or on the other side of the engine to intake manifold. If you measure the pipe needed from turbo to manifold on some of these alternative setups, there can be quite a bit of pipe work. Add in the volume of an intercooler and it makes you wonder is both setups don't have a similar volume of piping to pressurize before the intake manifold.
Sadly I don't have any figures for this, but I can at least follow the logic behind the thinking.
The only point I think rear mounted turbo's do suffer is the exhaust gas temps will be lower by the time they reach the turbo, so likely the flow rate will be slower also. Although I believe many will then use standard log style exhaust manifolds and coated exhaust parts to try and maintain the exhaust flow.
300bhp/ton said:
This is something I've tried to find out over the years as such a mod is quite popular on cars like my Camaro. Sadly I've never really found a satisfactory answer, mostly due to the age old problem of everyman and his boat getting confused between turbo lag and boost threshold. Those that do know the difference either haven't driven a rear mount turbo setup or if they have, they haven't driven a front mount setup to compare too.
That said, I've not yet spoken to an owner of a rear mount turbo setup who hasn't liked the end result and I've spoken to quite a few over the past 5 years or so.
Some of the theory I've garnered over the years runs along the lines of, most rear mount setup's don't run an intercooler and can achieve similar AIT's to front mount turbo setups running intercoolers.
Also the distance the turbo is from the intake manifold is not always as much as you might first think, it's just a straight run under the car and up into the engine bay. Few bends or turns.
Whereas on many front mount turbo setups, the turbo's can still be low down behind the engine, in the front bumper, ontop of the engine or on the other side of the engine to intake manifold. If you measure the pipe needed from turbo to manifold on some of these alternative setups, there can be quite a bit of pipe work. Add in the volume of an intercooler and it makes you wonder is both setups don't have a similar volume of piping to pressurize before the intake manifold.
Sadly I don't have any figures for this, but I can at least follow the logic behind the thinking.
The only point I think rear mounted turbo's do suffer is the exhaust gas temps will be lower by the time they reach the turbo, so likely the flow rate will be slower also. Although I believe many will then use standard log style exhaust manifolds and coated exhaust parts to try and maintain the exhaust flow.
A guy on the MX5 forums did thid many years ago he called it the "Turboot" (turbo in the boot) he didn't keep it long as it wasn't great BUT I suspect this was because it was only powered by 1600cc.That said, I've not yet spoken to an owner of a rear mount turbo setup who hasn't liked the end result and I've spoken to quite a few over the past 5 years or so.
Some of the theory I've garnered over the years runs along the lines of, most rear mount setup's don't run an intercooler and can achieve similar AIT's to front mount turbo setups running intercoolers.
Also the distance the turbo is from the intake manifold is not always as much as you might first think, it's just a straight run under the car and up into the engine bay. Few bends or turns.
Whereas on many front mount turbo setups, the turbo's can still be low down behind the engine, in the front bumper, ontop of the engine or on the other side of the engine to intake manifold. If you measure the pipe needed from turbo to manifold on some of these alternative setups, there can be quite a bit of pipe work. Add in the volume of an intercooler and it makes you wonder is both setups don't have a similar volume of piping to pressurize before the intake manifold.
Sadly I don't have any figures for this, but I can at least follow the logic behind the thinking.
The only point I think rear mounted turbo's do suffer is the exhaust gas temps will be lower by the time they reach the turbo, so likely the flow rate will be slower also. Although I believe many will then use standard log style exhaust manifolds and coated exhaust parts to try and maintain the exhaust flow.
On something like a 6ltr V8 I suspect it's much less of an issue.
Gassing Station | General Gassing | Top of Page | What's New | My Stuff