Okay, so I'm mental
Discussion
Right, I know some of you 'orrible mob have done stupid things to your Cerbs, so tell me. What are the most effective (or even, cost effective) mods to push a Cerb up the BHP and performance scale? I'm gonna go Emerald ECU for a start but what can be done to make this brute even more mental?
I could go down the supercharged route, but as the Cerb is already borderline sports car / supercar, and IMO I think that forced induction (turbo or super) is what makes the difference between these when the performance is what it is from this bracket of car, I'd rather stay as one of the worlds fastest production sports cars than a middling supercar.
I could go down the supercharged route, but as the Cerb is already borderline sports car / supercar, and IMO I think that forced induction (turbo or super) is what makes the difference between these when the performance is what it is from this bracket of car, I'd rather stay as one of the worlds fastest production sports cars than a middling supercar.
Well, you know how bhp is derived as being (torque x revs)/5252 ?
Essentially if you increase torque or revs you increase bhp. As you rev harder you gain more bhp. Increasing torque isn't always an easy thing to achieve without giving your engine a "head job" or increasing capacity.
But what if you simply *move* your peak torque to a place where you're making more revs? In other words, your current peak torque is probably around 5000rpm, or possibly even lower down the rev range. At that point your multiplication gives you a (relatively) low power figure.
What you want to do is to move your torque to an area further up the rev range, where you can benefit from twwo large numbers. This is in essence how the Whirlwind (and other) conversions work. The shorter induction gives you no more or less peak torque, but it moves this peak torque to a place in the rev range further up, where the multiplication gives you more power.
The secondary benefits of a smoother curve (both torque and power) will come if this kit is fitted at the same time as the Emerald and it is all mapped together.
Just to confirm what I wrote above, lets take 2 engines, both able to rev to 8000rpm and both with a peak torque figure of 400lbft. Engine number 1 develops its peak torque at 5000rpm whereas engine number 2 develops its peak torque at 7000rpm.
Engine number 1 power = (400 x 5000)/5252 = 381bhp
Engine number 2 power = (400 x 7000)/5252 = 533bhp
And don't listen to people who think you drive by torque. Power wins races. A gearbox dilutes or multiplies engine torque. If you want more torque, change down.
Essentially if you increase torque or revs you increase bhp. As you rev harder you gain more bhp. Increasing torque isn't always an easy thing to achieve without giving your engine a "head job" or increasing capacity.
But what if you simply *move* your peak torque to a place where you're making more revs? In other words, your current peak torque is probably around 5000rpm, or possibly even lower down the rev range. At that point your multiplication gives you a (relatively) low power figure.
What you want to do is to move your torque to an area further up the rev range, where you can benefit from twwo large numbers. This is in essence how the Whirlwind (and other) conversions work. The shorter induction gives you no more or less peak torque, but it moves this peak torque to a place in the rev range further up, where the multiplication gives you more power.
The secondary benefits of a smoother curve (both torque and power) will come if this kit is fitted at the same time as the Emerald and it is all mapped together.
Just to confirm what I wrote above, lets take 2 engines, both able to rev to 8000rpm and both with a peak torque figure of 400lbft. Engine number 1 develops its peak torque at 5000rpm whereas engine number 2 develops its peak torque at 7000rpm.
Engine number 1 power = (400 x 5000)/5252 = 381bhp
Engine number 2 power = (400 x 7000)/5252 = 533bhp
And don't listen to people who think you drive by torque. Power wins races. A gearbox dilutes or multiplies engine torque. If you want more torque, change down.
Okay Mars. I hear ya. I understand the theory.... so whats goin to give me more USEABLE and feelable power (and get that straight line 0-100 down)
EDIT: Just for info, I'm hitting the following according to engine advantages Witham:
305.3lb/ft @ 5657RPM
and
347.9BHP @ 6269RPM
EDIT: Just for info, I'm hitting the following according to engine advantages Witham:
305.3lb/ft @ 5657RPM
and
347.9BHP @ 6269RPM
Edited by V8Cerbera on Monday 19th February 00:58
This will. Torque curves that peak low are hard to manage when racing. Most racers prefer their torque to build with revs. In this way they get more overall power, and they don't get surprised as they exit a corner by a wave of oversteer.
The gearbox, if properly used, will keep the engine in the power band. My car (formerly Cyclones) does exactly that. It starts off strong and just gets stronger as you rev it. There are no surprises, in fact it's extremely docile around town. It has a more production car feel to it that some peaky sports cars. I'd go so far as to say it has a linear response to the throttle input, and ultimately, as you know, it delivers a serious amount of power.
The gearbox, if properly used, will keep the engine in the power band. My car (formerly Cyclones) does exactly that. It starts off strong and just gets stronger as you rev it. There are no surprises, in fact it's extremely docile around town. It has a more production car feel to it that some peaky sports cars. I'd go so far as to say it has a linear response to the throttle input, and ultimately, as you know, it delivers a serious amount of power.
Just noticed you have a 4.2 and I've been speaking about the 4.5s which have long induction from new. The 4.2s induction is near perfect I'm led to believe, already short and benefitting from decent throttle bodies.
You may not need an Emerald. Just a remap of your current ECU could give you the useable smooth power graph you're after. Much as I like Emeralds, there are few benefits to buying one over remapping your current one unless you plan on communicating with the ECU yourself (via a laptop).
You may not need an Emerald. Just a remap of your current ECU could give you the useable smooth power graph you're after. Much as I like Emeralds, there are few benefits to buying one over remapping your current one unless you plan on communicating with the ECU yourself (via a laptop).
Okay, hopefully you saw my last EDIT to my original post. I'm planning on a remap day with EA at some point as TBH she is badly over-fueling and even Leven said that the 4.2 responds well to a remap.
I think a remap due to the de-cat is in order anyway?
I assume from your wording in the last post that the standard TVR ECU EPROM is remappable?
I think a remap due to the de-cat is in order anyway?
I assume from your wording in the last post that the standard TVR ECU EPROM is remappable?
I don't believe it is remappable but they can certainly burn you a chip and replace yours with a new one. Quite honestly I don't know how they do it. An Emerald is certainly a PoP to map from an operator's point of view but you're looking at close to £1K for one which only makes sense if you're going to make several changes to the engine spec over the course of your ownership and I think the amount of possibilities for upgrades are lower with the 4.2 engine than the 4.5.
I honestly believe a bespoke map for every engine is worth the money you pay. With my Caterham I started off with 190bhp peak. Changed to an Emerald and had it mapped and achieved 205bhp peak but a whole lot more power everywhere else, and massively increase fuel economy. I went from a 165 mile range to 220 mile range (from a full tank). Win-win everywhere.
V8Cerbera said:
Okay, hopefully you saw my last EDIT to my original post. I'm planning on a remap day with EA at some point as TBH she is badly over-fueling and even Leven said that the 4.2 responds well to a remap.
I think a remap due to the de-cat is in order anyway?
I assume from your wording in the last post that the standard TVR ECU EPROM is remappable?
I think a remap due to the de-cat is in order anyway?
I assume from your wording in the last post that the standard TVR ECU EPROM is remappable?
Not really, the best you will see from a remap on a 4.2 is 10-15bhp peak and maybe some minor gains inthe rest of the range. I think you stated in another thread that "your" car already feels very quick so that *may* put yourcar in the 350bhp bracket, which is very good for a 4.2. If your car has no mods at all then the best you will see from a remap may only be 5bhp. Best bet would be to get it down to the Surrey Rolling Road Day on Saturday and see what sort of power it makes, Charlies rollers have seen lots of Cerbs so will give you the ideal opportunity to do a comparison.
Jules.
mars said:
Well, you know how bhp is derived as being (torque x revs)/5252 ?
Essentially if you increase torque or revs you increase bhp. As you rev harder you gain more bhp. Increasing torque isn't always an easy thing to achieve without giving your engine a "head job" or increasing capacity.
But what if you simply *move* your peak torque to a place where you're making more revs? In other words, your current peak torque is probably around 5000rpm, or possibly even lower down the rev range. At that point your multiplication gives you a (relatively) low power figure.
What you want to do is to move your torque to an area further up the rev range, where you can benefit from twwo large numbers. This is in essence how the Whirlwind (and other) conversions work. The shorter induction gives you no more or less peak torque, but it moves this peak torque to a place in the rev range further up, where the multiplication gives you more power.
The secondary benefits of a smoother curve (both torque and power) will come if this kit is fitted at the same time as the Emerald and it is all mapped together.
Just to confirm what I wrote above, lets take 2 engines, both able to rev to 8000rpm and both with a peak torque figure of 400lbft. Engine number 1 develops its peak torque at 5000rpm whereas engine number 2 develops its peak torque at 7000rpm.
Engine number 1 power = (400 x 5000)/5252 = 381bhp
Engine number 2 power = (400 x 7000)/5252 = 533bhp
And don't listen to people who think you drive by torque. Power wins races. A gearbox dilutes or multiplies engine torque. If you want more torque, change down.
Essentially if you increase torque or revs you increase bhp. As you rev harder you gain more bhp. Increasing torque isn't always an easy thing to achieve without giving your engine a "head job" or increasing capacity.
But what if you simply *move* your peak torque to a place where you're making more revs? In other words, your current peak torque is probably around 5000rpm, or possibly even lower down the rev range. At that point your multiplication gives you a (relatively) low power figure.
What you want to do is to move your torque to an area further up the rev range, where you can benefit from twwo large numbers. This is in essence how the Whirlwind (and other) conversions work. The shorter induction gives you no more or less peak torque, but it moves this peak torque to a place in the rev range further up, where the multiplication gives you more power.
The secondary benefits of a smoother curve (both torque and power) will come if this kit is fitted at the same time as the Emerald and it is all mapped together.
Just to confirm what I wrote above, lets take 2 engines, both able to rev to 8000rpm and both with a peak torque figure of 400lbft. Engine number 1 develops its peak torque at 5000rpm whereas engine number 2 develops its peak torque at 7000rpm.
Engine number 1 power = (400 x 5000)/5252 = 381bhp
Engine number 2 power = (400 x 7000)/5252 = 533bhp
And don't listen to people who think you drive by torque. Power wins races. A gearbox dilutes or multiplies engine torque. If you want more torque, change down.
this is one of the best posts i've read in a long time
Cyclone1 said:
V8Cerbera said:
Okay, hopefully you saw my last EDIT to my original post. I'm planning on a remap day with EA at some point as TBH she is badly over-fueling and even Leven said that the 4.2 responds well to a remap.
I think a remap due to the de-cat is in order anyway?
I assume from your wording in the last post that the standard TVR ECU EPROM is remappable?
I think a remap due to the de-cat is in order anyway?
I assume from your wording in the last post that the standard TVR ECU EPROM is remappable?
Not really, the best you will see from a remap on a 4.2 is 10-15bhp peak and maybe some minor gains inthe rest of the range. I think you stated in another thread that "your" car already feels very quick so that *may* put yourcar in the 350bhp bracket, which is very good for a 4.2. If your car has no mods at all then the best you will see from a remap may only be 5bhp. Best bet would be to get it down to the Surrey Rolling Road Day on Saturday and see what sort of power it makes, Charlies rollers have seen lots of Cerbs so will give you the ideal opportunity to do a comparison.
Jules.
this is good sound advice Jules. I think I'll pack up and go home, you guys know your stuff
mars said:
Jules/Joolz, what holds a *good* 4.2 at about the 360bhp mark when a similarly *good* 4.5 can achieve so much more? Surely it can't be simply the 300cc difference? Are they different heads/valve sizes or compression ratios?
I'd love to know why they have different induction systems?
TooTall Paul said:
Thats a very interesting pic on your profile AJP GRIFF,It shows what appears to be the ajp with link pipes on the manifolds! It always makes me wonder why TVR never ran the cars with short induction and link pipes. Judging by the pic they obviously tested them.
I ***think*** that the link pipe you see is actually a brace for the manifolds?It is an interesting pic though,it'll be all the more interesting when i finally have one to drive
It does look more like a brace than a link. It's only between one branch of the manifold from each side rather than from the pipe downwind of the collector.
This project of yours will be very interesting. There were a couple of TVR Power supercharged Chims at the West Mids meeting yesterday. Personally I prefer the AJP engine but both methods result in some quite serious power.
This project of yours will be very interesting. There were a couple of TVR Power supercharged Chims at the West Mids meeting yesterday. Personally I prefer the AJP engine but both methods result in some quite serious power.
Gassing Station | Cerbera | Top of Page | What's New | My Stuff