just dynoed the cerb

just dynoed the cerb

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Discussion

spitfire4v8

Original Poster:

4,018 posts

195 months

Thursday 15th September 2022
quotequote all
Thought it was about time I mapped my own cerb .. seems to be doing ok ..

4.2 top end, 4.5 bottom end, ported and skimmed heads, ported intakes etc etc ..

gruffalo

7,848 posts

240 months

Thursday 15th September 2022
quotequote all
Very healthy:-)

LucyP

1,773 posts

73 months

Thursday 15th September 2022
quotequote all
So why don't you ever drive it? It's done 47 miles in nearly 5 years, so it doesn't really matter what power it is producing. At less than 10 miles a year, you could push it without worrying.

A good example of how TVR used to exaggerate power figures and used to give the press one engine and the customers a totally different one.

spitfire4v8

Original Poster:

4,018 posts

195 months

Thursday 15th September 2022
quotequote all
It's none of your business really but 4 other sports cars means the cerb never gets used plus mrs spitfire doesn't like the closed in cabin, she prefers the more open nature of the Tuscan cabin so that's what we've used more recently though even that hasn't moved for 2 years I think... time to let someone else have the use of the cerb now, i've got my eye on another.

Gladers01

1,219 posts

62 months

Thursday 15th September 2022
quotequote all
spitfire4v8 said:
It's none of your business really but 4 other sports cars means the cerb never gets used plus mrs spitfire doesn't like the closed in cabin, she prefers the more open nature of the Tuscan cabin so that's what we've used more recently though even that hasn't moved for 2 years I think... time to let someone else have the use of the cerb now, i've got my eye on another.
Very impressive and looks like a smooth power delivery, why do the torque and Bhp lines always seem to cross at 5250rpm ? thumbup

LeighW

4,935 posts

202 months

Thursday 15th September 2022
quotequote all
Gladers01 said:
spitfire4v8 said:
It's none of your business really but 4 other sports cars means the cerb never gets used plus mrs spitfire doesn't like the closed in cabin, she prefers the more open nature of the Tuscan cabin so that's what we've used more recently though even that hasn't moved for 2 years I think... time to let someone else have the use of the cerb now, i've got my eye on another.
Very impressive and looks like a smooth power delivery, why do the torque and Bhp lines always seem to cross at 5250rpm ? thumbup
HP = Torque X RPM/5252. smile

ETA I may be due a parrot?

Gary C

13,696 posts

193 months

Thursday 15th September 2022
quotequote all
Gladers01 said:
, why do the torque and Bhp lines always seem to cross at 5250rpm ? thumbup
Err, maths ?

Whoosh ?

SteveStrange

5,701 posts

227 months

Thursday 15th September 2022
quotequote all
spitfire4v8 said:
It's none of your business really but 4 other sports cars means the cerb never gets used plus mrs spitfire doesn't like the closed in cabin, she prefers the more open nature of the Tuscan cabin so that's what we've used more recently though even that hasn't moved for 2 years I think... time to let someone else have the use of the cerb now, i've got my eye on another.
I would have been approximately 400 times ruder in my reply to that sort of post.

Some very strange people about.

robsco

7,874 posts

190 months

Friday 16th September 2022
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LucyP said:
A good example of how TVR used to exaggerate power figures and used to give the press one engine and the customers a totally different one.
Is it? How?

It has a virtually standard 4.5 bottom end, with some light porting (which achieves what, 5-10bhp at most?), producing factory 4.5 stated outputs a quarter of a century later. Am I missing something?

105.4

4,214 posts

85 months

Friday 16th September 2022
quotequote all
robsco said:
LucyP said:
A good example of how TVR used to exaggerate power figures and used to give the press one engine and the customers a totally different one.
Is it? How?

It has a virtually standard 4.5 bottom end, with some light porting (which achieves what, 5-10bhp at most?), producing factory 4.5 stated outputs a quarter of a century later. Am I missing something?
It looks very healthy to me.

I always thought the 4.2s were around 380 in real world figures?

What’s the difference between the 4.2 and the 4.5 heads?

SteveStrange

5,701 posts

227 months

Friday 16th September 2022
quotequote all
105.4 said:
robsco said:
LucyP said:
A good example of how TVR used to exaggerate power figures and used to give the press one engine and the customers a totally different one.
Is it? How?

It has a virtually standard 4.5 bottom end, with some light porting (which achieves what, 5-10bhp at most?), producing factory 4.5 stated outputs a quarter of a century later. Am I missing something?
It looks very healthy to me.

I always thought the 4.2s were around 380 in real world figures?

What’s the difference between the 4.2 and the 4.5 heads?
0.3. HTH.

getmecoat

FarmyardPants

4,221 posts

232 months

Friday 16th September 2022
quotequote all
Great numbers Jools. Nice torque, must be fun to drive.

Heads are the same, I think top end means throttle bodies/induction in this instance.

spitfire4v8

Original Poster:

4,018 posts

195 months

Friday 16th September 2022
quotequote all
Its a 4.5 bottom end (diamond pistons) . Heads have had the rough edges and machining steps removed and skimmed, 4.2 intakes have had their machining steps removed, spindles thinned .. X pipe exhaust and remap. All that work gains you about 60-80hp over a std 4.2 as it was (std 4.2 would be around 340-360hp on my dyno)

power and torque only crosses there if the power is bhp and torque is lb.ft and yes they are linked by maths. If you have Nm or PS or KW they cross at different revs, but still linked by maths so as long as you use the same units the graphs will always cross at a fixed rev point, IYSWIM

Jhonno

6,036 posts

155 months

Friday 16th September 2022
quotequote all
spitfire4v8 said:
Its a 4.5 bottom end (diamond pistons) . Heads have had the rough edges and machining steps removed and skimmed, 4.2 intakes have had their machining steps removed, spindles thinned .. X pipe exhaust and remap. All that work gains you about 60-80hp over a std 4.2 as it was (std 4.2 would be around 340-360hp on my dyno)

power and torque only crosses there if the power is bhp and torque is lb.ft and yes they are linked by maths. If you have Nm or PS or KW they cross at different revs, but still linked by maths so as long as you use the same units the graphs will always cross at a fixed rev point, IYSWIM
Not far off mine! Very similar spec! I've added my x-pipe now too.. Maybe one day if I get round to saving up for Emerald I'll see what it makes now.

Gazzab

21,365 posts

296 months

Friday 16th September 2022
quotequote all
That’s a lot more than mine. Mines putting out about 0 bhp

Gladers01

1,219 posts

62 months

Friday 16th September 2022
quotequote all
spitfire4v8 said:
Its a 4.5 bottom end (diamond pistons) . Heads have had the rough edges and machining steps removed and skimmed, 4.2 intakes have had their machining steps removed, spindles thinned .. X pipe exhaust and remap. All that work gains you about 60-80hp over a std 4.2 as it was (std 4.2 would be around 340-360hp on my dyno)

power and torque only crosses there if the power is bhp and torque is lb.ft and yes they are linked by maths. If you have Nm or PS or KW they cross at different revs, but still linked by maths so as long as you use the same units the graphs will always cross at a fixed rev point, IYSWIM
Thanks for clarifying, learn something new everyday! How would the graph compare to a similarly fettled Cerbera speed 6? Back in the day the Tvr sales brochure was quoting 400 Bhp, which sounds a tad optimistic scratchchin

105.4

4,214 posts

85 months

Friday 16th September 2022
quotequote all
SteveStrange said:
105.4 said:
robsco said:
LucyP said:
A good example of how TVR used to exaggerate power figures and used to give the press one engine and the customers a totally different one.
Is it? How?

It has a virtually standard 4.5 bottom end, with some light porting (which achieves what, 5-10bhp at most?), producing factory 4.5 stated outputs a quarter of a century later. Am I missing something?
It looks very healthy to me.

I always thought the 4.2s were around 380 in real world figures?

What’s the difference between the 4.2 and the 4.5 heads?
0.3. HTH.

getmecoat
Berk

hehe

Imran999

363 posts

167 months

Friday 16th September 2022
quotequote all
That’s bloody brilliant, even by todays standards.
Now I’m even more sad that my car didn’t spend time at K&C’s before leaving the UK.
If it wasn’t for the sheer hassle of shipping, I would seriously consider sending it back for a visit.

On another note, I continue to marvel at how sensible/restrained the community on this forum are ;-)

105.4

4,214 posts

85 months

Friday 16th September 2022
quotequote all
Gazzab said:
That’s a lot more than mine. Mines putting out about 0 bhp
What’s up with yours Gaz?

Gazzab

21,365 posts

296 months

Friday 16th September 2022
quotequote all
105.4 said:
Gazzab said:
That’s a lot more than mine. Mines putting out about 0 bhp
What’s up with yours Gaz?
I am the master of engine rebuilds. Think I have had 2 or 3 on the current Cerb and as many on the previous 2 cerbs.