Turbo upgrade on RV8

[SILICONEKID340HP]

phazed said:

spitfire4v8 said:

I don't think you'll have too many issues with the sort of cam you're using. Supercharged engines can have issues with blow-through, but in a turbo install you have higher pressures in the enxhaust so blow through issues don't occur like the do in positive displacement supercharger installs. How high is your CR? 11:1? 12:1?

I'm seriously thinking about this for next year.

Mine's running about 12:1 with a very smooth highish lift cam that will give at least 340 brake and 350 torques,

Given this state of tune, I'm sure many of us would like a very approximate indication of power increase?

God knows what mine is ! i did not get a build sheet in the end !
Hi Peter,changed your name

[macdeb]

Would be good to be able to find out what comp' ratios are. I know how to do it with engine stripped but think there is another way by some calculation with cylinder pressure. It's obviously crucial to know I'd have thought before bolting one on. Anyone?

[phazed]

Correct, .

I think yours is about 340 horses!

[macdeb]

phazed said:

Correct, .

I think yours is about 340 horses!

almost

[Ribol]

macdeb said:

...........try to add something constructive/informative to the post.

macdeb said:

SILICONEKID340HP said:

Can i give you a kiss

No, but we can dance

I doubt I could compete with your efforts but willing to try

[macdeb]

Getting bored now

[Goaty Bill]

That may have been a olive branch...

[slideways]

macdeb said:

Would be good to be able to find out what comp' ratios are. I know how to do it with engine stripped but think there is another way by some calculation with cylinder pressure. It's obviously crucial to know I'd have thought before bolting one on. Anyone?

Do a compression test then divide that by 14.7.
I have a low 7.5:1 cr and 110 across all cylinders

HTH

[macdeb]

slideways said:

macdeb said:

Would be good to be able to find out what comp' ratios are. I know how to do it with engine stripped but think there is another way by some calculation with cylinder pressure. It's obviously crucial to know I'd have thought before bolting one on. Anyone?

Do a compression test then divide that by 14.7.
I have a low 7.5:1 cr and 110 across all cylinders

HTH

Cheers Richard, though that gives me 11.6:1 from memory I'll do another test.

[neal1980]

slideways said:

Do a compression test then divide that by 14.7.
I have a low 7.5:1 cr and 110 across all cylinders

HTH

Why did you go so low Richard?

Any numbers yet?

[dbv8]

Using a compression tester to calculate your CR is a myth.
Its more complicated than that.

Dont ask me to expand further please.

[phazed]

I'm sure I had 220psi all round, that doesn't work

[macdeb]

Just checked again as I found my previous test figures at between 175-180 which at a minimum would give 11.9:1 and Peters would be 14.9:1
Derek, is it 13th at Shakey? [off topic sorry but been trying to call you]
I know mechanically for calculation you need;
Cylinder bore
piston stroke
Head gasket thickness
Cylinder head volume
piston volume [if any]
piston deck clearance
But did hear from somewhere else that an approximation can be gained from pressure test and some of above, anyone?

Edited by macdeb on Tuesday 2nd October 16:54

Edited by macdeb on Tuesday 2nd October 17:01

[slideways]

neal1980 said:

slideways said:

Do a compression test then divide that by 14.7.
I have a low 7.5:1 cr and 110 across all cylinders

HTH

Why did you go so low Richard?

Any numbers yet?

That was the choice of the the engine builder but it drives like a pussy cat round town, and a scolded cat if I even think about pressing the loud pedal.
No numbers yet still ironing out niggles, got the engine temps to stay at a tidy 84degs, with my new fan arrangement, just a battery drain to find and good to go

Edited by slideways on Tuesday 2nd October 17:12

[phazed]

phazed said:

I'm sure I had 220psi all round, that doesn't work

Just found my test results from my old 4.6 engine with high comp 4.0 pistons..

Minimum of 205 to a maximum of 225psi.

Since then, heads have been overhauled and block decked so probably a tad more!

[Ribol]

phazed said:

phazed said:

I'm sure I had 220psi all round, that doesn't work

Just found my test results from my old 4.6 engine with high comp 4.0 pistons..

Minimum of 205 to a maximum of 225psi.

Since then, heads have been overhauled and block decked so probably a tad more!

Surely different cam timing/overlap with have some bearing on the cylinder pressure readings?

Meanwhile the mechanical CR isn't going to be affected, so how can there be a relationship between the two?

[Bluebottle]

slideways said:

Do a compression test then divide that by 14.7.
I have a low 7.5:1 cr and 110 across all cylinders

HTH

Don't think that works, as that would give u swept volume less any valve overlap
e.t.a.
calculating CR video

Edited by Bluebottle on Thursday 11th October 14:51

[phazed]

I think all this maths is taking me out of my comfort zone!

[SILICONEKID340HP]

phazed said:

I think all this maths is taking me out of my comfort zone!

Are you "phazed"

[neal1980]

slideways said:

That was the choice of the the engine builder but it drives like a pussy cat round town, and a scolded cat if I even think about pressing the loud pedal.
No numbers yet still ironing out niggles, got the engine temps to stay at a tidy 84degs, with my new fan arrangement, just a battery drain to find and good to go

Edited by slideways on Tuesday 2nd October 17:12

Whats the new setup Richard on the fans I may need something else, dont see you post on here alot these days. Hope your all good