Intake manifold and porting...

[Chuffmeister]

How far down did TVR port the intake manifold? My 500 is the standard 44mm, however, i'd like to know how far down the ports the ACT/ V8D 45mm versions are actually ported in comparison; or; how far the 500 44mm intake is ported in comparison to the standard 400 intake? Is it just the apertures of the ports that have been opened or have they been ported all the way down?

What would I need to do to my 44mm intake to make it the same as the V8D/ ACT intakes?

[Chuffmeister]

Cheers Alex. I've had an offer to open the ports to 45mm via CNC. I have a die grinder with tungsten carbide bits. Just wondered how much is CNC port opening and how much actual porting. If the ACT and V8D only have the ports opened and the rest as standard, then it is an easy enough job.

[Chuffmeister]

Thanks for the offer Alex. Is there any difference between the ACT ones and the V8D apart from the price?

I was considering having the 44mm CNC'd out to 45mm, but if it also needs porting to meet the same spec as the V8D/ACT ones, then its maybe too much grief. I did my own trumpet base and it took me a couple of afternoons, but if the intake needs loads of porting, then I may give it a wide birth.

[Chuffmeister]

Just sent him an e-mail.

[Chuffmeister]

Thanks spend/ Bobby. This is the type of technical stuff I'm after. Spend, in your opinion, what are the advantages of the standard 38mm, against the 44mm, against the 45mm? Is there any advantage of having the 45mm intake over the 44mm and what sort of power/ torque increase could you expect? Is there any advantage of either the 44/45mm over the 38mm if the porting is only done at each end?

[Chuffmeister]

Very interesting info here and thanks for your replies.

Okay, so porting myself is over ambitious! So would upgrading my 44mm to a 45mm intake really make a difference to airflow? If you recall, I made my own trumpet base (see below). The trumpets have a 46.5ID and the base tapers to 44mm to match the mouth of the intake manifold. So would this help increase air speed or would the 44mm taper reduce air flow?

I'm planning on upgrading to MS. I have the larger bore induction stuff and a 72mm plenum on its way. I have made my own flared trumpets.

-With this in mind and for bang for buck, is it worth me upgrading my 44mm intake manifold to a 45mm?
-What gains would I likely see?
-The cylinder head port end of my manifold is already opened to stage 3 (being a 500). Would a wider mouth at the trumpet base end by 1mm make a big difference?
- Would my tapered trumpets not already increase the air speed in the same way as the large diameter intake mouth?

I appreciate that a lot of these questions may be difficult to quantify without a bench test/ dyno, but your collective experience is of a great benefit. I don't want to splash out £230 for a 1hp gain.

[Chuffmeister]

Sardonicus said:

greed I would hope that running full sequential fuel would be an improvement but who knows? the improvements may be minimal you cant tell with the RV8

I guess it all depends on the state of tune. For most of us, fully sequential wouldn't make much of an impact, however if you're running a really wild cam and timing, then it may be of some benefit.

[Chuffmeister]

Can you not equalise the length of the runners with the trumpets? Why are the original trumpets in the 4:4 configuration? If the runners/ trumpets aren't an equal length in the stock engine and if air volume in the plenum is an issue with the RV8, why have a trumpet base at all? Would it not be better to have a larger plenum fitted directly to the intake manifold or is it about gradually changing the direction of the air once it comes into the plenum to get it around the bend in the intake?

The other thing, with respect to EFI vs carbs, is that depending on the ECU, you can have more control over the fuelling and spark, however, there is a common view that carbs can yeild more power, which would suggest that it is more about air volume and the and less about precision timing of the fuel/ spark.

What about using one of these to add bike carbs? Would this likely cause emmissions issues?

Edited by Chuffmeister on Saturday 13th December 15:53

[Chuffmeister]

Bobby Shaftoe said:

In my humble opinion, going from 44mm to 45mm would be a waste of time. The best bang for the buck in your case would be replacing your mild Kent H218 camshaft with a wilder grind, and increasing the compression ratio to suit.

You have a point. V8D contacted me to say that they haven't bench tested an intake manifold by itself, only the trumpet base/ manifold combo. The ECU and cam are on my list. I just wanted know the quantifiable gains from 44-45mm intake

[Chuffmeister]

This looks fantastic. Whatvare TA heads?



http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Chuffmeister]

carsy said:

This is evidence that 45mm does work. AIUI this graph shows Griffdudes 4.5 going from 38mm to a ported inlet manifold and one of Jools`s 45mm blended bases. Increase everywhere and 20bhp at the top end.

Ideally, you would need to test each component individually to determine which one causes the increase in BHP.

- standard trumpet base and intake manifold
- blended base and standard 38mm intake
- standard trumpet base and 45mm intake
- blended base and 45mm intake.

A lot of work, but it would be interesting to see which part of the intake would make the largest increase. In my case, I was asking whether I would see a real world increase from 44mm to 45mm. However, this aside, it is the trumpet base that appears to be the most important thing, to help increase the speed the airflow.

Having contacted V8D, they said they've never tested the 45mm intake manifold by itself, only in conjunction with the 45mm trumpet base. However, there have been plenty of tests with trumpet bases by themselves, which appear to yeald good results (including the rather lovely looking blended base).

Reading between the lines (and I am probably comletely wrong), if there was a huge increase to be had between the intake manifolds, then these would have been individually tested and marketed as such to increase revenues of the companies that produce them. It is easy to sell two items for around £400 on the back of a 15/20BHP increase, but more difficult to sell one for 200 that may only yeild 1-2bhp, whilst the other for the same price that gives you a potental 14-18bhp. Intake or trumpet base, which is it? Chicken and egg....

There is probably a noticeable increase from 38-45mm, but still nobody can quantify (not even V8D) the difference in BHP the intake manofold makes. It appears that nobody has tested the 38/44/45mm back to back too see what BHP or torque increase they give. So my original question wa, would there be a difference in output between my 44mm and 45mm intakes? Not even V8D could tell me the answer. If somebody has a RR and the time, then I'd happily spend a day with them and use my Chim to see if there was a difference and what that difference i

Edited by Chuffmeister on Sunday 14th December 18:51

[Chuffmeister]

Bobby Shaftoe said:

Thanks carsy i was hoping someone would come up with some evidence, any idea what heads and throttle plate size this guy is running?

ETA - and by blended base, do you mean a base with no trumpets at all?

Edited by Bobby Shaftoe on Sunday 14th December 18:52

http://www.kitsandclassics.co.uk/engine-ecu/#conte...

Edited by Chuffmeister on Sunday 14th December 19:00