TVR 350i engine size???

[trevbeadle]

Help!
I have a 1987 TVR 350i, the V5 from DVLA shows the engine size as 3498cc, engine number 37A00715C! My insurance company queried this when I first insured it, they said 'surely you mean 3528cc, that's the early V8 engine size?'. I can find no Rover engine of 3498cc....any ideas?



Trev

[Number 7]

3528cc is correct

[Number 7]

Number 7 said:

3528cc is correct

ETA - unless it is a special to keep within a competition 3.5l capacity limit, but this would be highly unlikely

[PHJayV8]

It must have been an error when the cars were registered from new, my '87 350i reg document said the same..... interesting

[mrzigazaga]

Hi..I think the initial displacement for the RV8 was 3528cc...I think some TVR's might of had a slightly less accurate engine declaration on the V5..Although it was more not less..Probably a genuine mistake...

[TA14]

Number 7 said:

Number 7 said:

3528cc is correct

ETA - unless it is a special to keep within a competition 3.5l capacity limit, but this would be highly unlikely

I've often wondered about the 3498cc figure speculating whether it's just a YTS guy filling in the papers or some tax avoidance scam for some european country and so they filled in the english ones that way to look genuine.

[Number 7]

It's the product of a 88.90mm bore x 71.12mm stroke (yes, I had to look that up)

[TA14]

That's OK for the 3528 figure but where did the other (widely used and incorrect) figure come from?

[adam quantrill]

Number 7 said:

It's the product of a 88.90mm bore x 71.12mm stroke (yes, I had to look that up)

That comes to 3532cc, and it would be the displacement, not the capacity (i.e. it ignores the combustion chamber.) If you figure in a 9.8 compression ratio that comes to 3899cc. So nothing seems to add up.....

[TA14]

So by my calcs 3.5 squared x 2.8 x pi x 0.25 x 8 = 215.51324(or 5) ci so 215 engines should be 216 really.

[Number 7]

adam quantrill said:

That comes to 3532cc, and it would be the displacement, not the capacity (i.e. it ignores the combustion chamber.) If you figure in a 9.8 compression ratio that comes to 3899cc. So nothing seems to add up.....

Yes, I'd overlooked combustion chamber volume. If we take 30cc each, that's an additional 240cc, making a total of around 3,770cc. As you say, doesn't stack up.

[GadgeS3C]

I've never seen engine size/cubic capacity/displacement described as including combustion chamber volume before - am I missing something?

[TA14]

GadgeS3C said:

I've never seen engine size/cubic capacity/displacement described as including combustion chamber volume before - am I missing something?

No, it's just people being a bit daft. Capacity is recorded as the swept displacement. We do have three unanswered questions though:
where does the 3498 cc come from?
where does the 3528 cc come from?
where does the 215 ci come from?

[Number 7]

TA14 said:

No, it's just people being a bit daft. Capacity is recorded as the swept displacement. We do have three unanswered questions though:
where does the 3498 cc come from?
where does the 3528 cc come from?
where does the 215 ci come from?

Checking Des Hammill's book, 3528cc is the product of the bore and stroke figures given earlier - there must be some rounding differences (how many decimal places do you take Pi to etc?) and this figure ignores combustion chamber volume. 215 cu inch is a rounded down equivalent, as I think US engines are only described in whole numbers. 3498cc is an error (subject to my earlier caveat).

[TA14]

Number 7 said:

TA14 said:

No, it's just people being a bit daft. Capacity is recorded as the swept displacement. We do have three unanswered questions though:
where does the 3498 cc come from?
where does the 3528 cc come from?
where does the 215 ci come from?

Checking Des Hammill's book, 3528cc is the product of the bore and stroke figures given earlier - there must be some rounding differences (how many decimal places do you take Pi to etc?) and this figure ignores combustion chamber volume. 215 cu inch is a rounded down equivalent, as I think US engines are only described in whole numbers. 3498cc is an error (subject to my earlier caveat).

Dear No 7 your post does not answer any of the outstanding questions: 3528 is not the product of the bore and stroke figures whether you do the maths in imperial and then convert or do the maths in metric; try it yourself, I used ten significant figures. Note my earlier post and Adams. Combustion chamber volume is not used in displced cap calcs. The americans do not use a rounding down regime, eg http://www.my69z28.com/id18.html
although 3498 is not correct it is not necessarily an error, as you know; for example the 390s were registered as 350s... I wondered where it does come from.

[QBee]

I know very little and am about to prove it......but if the cylinder heads were changed by TVR to smaller combustion chambers to increase the compression ratio over the standard, 0-60 by sundial, Rover unit, would could this reduce the ccs by 30, from 3528 to 3498?

My 3952 cc Chimaera 400 had 28.5 cc combustion chambers.
My 4988(?) cc Chimaera 500 has 33 cc combustion chambers, actually to keep the compression ratio sane. So 400 heads cannot be used on 500 engines.

[GadgeS3C]

QBee said:

I know very little and am about to prove it......but if the cylinder heads were changed by TVR to smaller combustion chambers to increase the compression ratio over the standard, 0-60 by sundial, Rover unit, would could this reduce the ccs by 30, from 3528 to 3498?

My 3952 cc Chimaera 400 had 28.5 cc combustion chambers.
My 4988(?) cc Chimaera 500 has 33 cc combustion chambers, actually to keep the compression ratio sane. So 400 heads cannot be used on 500 engines.

No, because combustion chamber volume isn't part of cubic capacity.

Of course, TVR may have added combustion chamber volume to make the numbers sound more impressive

[Rockettvr]

My assumption was that engine sizes were for swept volume rather than total cylinder capacity ?

[Englishman]

Rockettvr said:

My assumption was that engine sizes were for swept volume rather than total cylinder capacity ?

Correct.

From Wikipedia:

'Engine displacement is the volume swept by all the pistons inside the cylinders of a reciprocating engine in a single movement from top dead centre (TDC) to bottom dead centre (BDC). It is commonly specified in cubic centimetres (cc), litres (l), or (mainly in North America) cubic inches (CID). Engine displacement does not include the total volume of the combustion chamber.'

[QBee]

Well that has cleared that up nicely