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MG MGB GT V8 Factory Originals Technical - wing mods to fit RV8 Manifolds

I intend to replace my "exhausted" tubular exhaust system with an RV8 system. (R/B '81 GT) Can people help with the wing mod specs etc involved in doing this. Cant find any ref to this in archives. Cheers.
D R Smith

I believe (I haven't got this far yet) that when you buy the reinforcing rings that you need to weld around the holes in the inner wings, you get a template for the hole cutting. Someone correct me if I'm wrong.
Mike
Mike Howlett

Thanks for info Mike, when browsing i noticed that one car had a shroud added to mask the hole and pipes, on outer aspect of inner wing. I presume this is not a part of the kit. I'm a bit concerned about ingress of water and gunge to engine bay as i use the car all year round. Danny.
D R Smith

I've run mine with an RV8 system since April, and no real sign of water or muck in the engine bay.

MGBhive gave me a template for cutting the holes, and I reinforced them with sheet steel, as I was unwilling to pay the price asked for Rover inserts.


Mike
Michael barnfather

Hi Michael, Glad to hear that you experience very little ingress of muck to engine bay. Any wrinkles i should know before starting the job? Have you found any differences in pick up etc since fitment? I'm surprised that there are so few comments re these manifolds from members, considering that it involves attacking the structure of car body to fit. Danny
Danny

Danny, lots on this subject in the Archive threads.....
David

Danny,
not really, but David is right, lots of info in the archives.

I was fortunate in that I was working on a new heritage shell, so I could get at everything easily, the strenghteners were spot welded into place, then seam welded around the outside for more strength.

Actually they didn't line up exactly with the manifolds (MGBhive) so had to be tweeked a little.

The stainless BHive system (which was the cheapest), was not the best of fits, and had to go back to them to re-allign the manifolds, it also hangs a bit low at the back (see archives) so had to be bent slightly..

It is however a marvelous sounding system, and the engine seems to rev more easily than with the old block hugger system.

Mike
Michael barnfather

Thanks to all for comments and info. Will troll through archives. Danny.
Danny

Can I voice a lone dissent. I realize the archives are filled with praise for the RV8-style headers. I swapped out a set of mild steel, Jet-Hotted block-huggers for a mild steel set of Jet-Hotted RV8-style. Few things:

1. I don't perceive any difference whatsoever in performance. The car is silly fast either way.

2. The car is a bit louder and seems more metallic sounding with the RV8s.

3. I don't perceive any difference in cooling (for me, the only overheating problem I've ever had -- and I continue to -- is at idle, where the RV8 holes in the fenders don't suck air out into the wheel wells; car never overheated at speed).

4. I am dubious about those big holes in my fender wells. It is a near show-quality car and I was super careful in cutting but I can't imagine I haven't compromised the strength of the front clip somewhat. I did it with the engine in situ, so I could not easily add the reinforcing rings. I just belled the hole edges a bit. Looks good though.

5. I am worried about them melting my tires. The front tires now get very hot at low speeds or when stopped. You have to be careful to park with the front wheels facing straight forward. I have fairly gummy Yokohama tires though.

5. I am a bit worried about overheating my brake lines. I re-plumbed the lines but they are still not very far from the headers.

6. One change is that the oil temp has decreased from about 95 deg. C to 80 deg. C. I guess this is because there are no headers running down the side of the oil pan. That's good, but I use Mobil 1 and I don't think it really cares one way or the other. No difference in water temp though.

7. I do notice a bit of gunk gettind into the engine bay. Not too severe, but I do drive the car every day and a bit of crud has gotten in, presumably from my long dirt driveway that's often kind of muddy.

8. In the rain, I wonder if the headers will crack because the front wheels are dousing them with water, at least during turns.

On balance, unless there's a horrible power loss that has escaped me, I think I'd humbly suggest you stick with the block-huggers.
Fred Testa

Hi Fred, Thanks for the comments, and yes i agree with most, particularly that cutting a big hole in inner wing doesnt sound the best way of improving a car. Yes I also wonder about cold water on red hot pipes...... Im not particularly looking for power increases, overriding reason for me is that im fed up struggling with inaccessible bolts and maneouvering with the driver side set to remove or replace,grrrrr!! Danny
Danny

Interesting post Fred ! I have heard that the holes can lead to higher noise levels at speed.

Jet-hot coating does keep the temperature down and seems to be the key to operating block-huggers in very hot climes.
Roger

Hi Fred, your comments are noted, I lagged the pipes, but still had cooling problems at rest, these were cured by fitting louvres on each side of the RV8 bonnet hump, facing backwards, you can see the heat haze when stuck in traffic, and I get a wonderful cloud of steam out of them every time I start up when it's been raining !

I have offset wheels, so the tyres are further away from the downpipes ,but nevertheless I always park with the wheels straight ahead just in case.

I too rerouted the brake lines, but they are quite close to the exhaust, so I've also sleeved them in heatproof sleeving for good measure.

I don't know if any more power is produced, but the engine does seem to pick up revs faster with this system (but it is also a slightly larger bore than the old one, with only one tail silencer instead of the usual two.

Mike
Michael barnfather

There is a lot in the archives and I tried to put up a step by step description of my own V8 conversion in May or so.

The reinforcement rings were well worth the money. No particular ingress of dirt. No brake or tyre heating problems after re-routing the brake lines. I have 7" tyres and no problems there. An increase in acceleration, I think and definitely an improvement in the heating problem with a marked decrease in underbonnet temperatures. My RV8 conversion was into a single stainless steel system.
Marc

Thanks Marc, Can the Manifolds be fitted with engine in car?
Danny

Danny,

My RV8 manifolds from the MGBHive couldn’t be fitted with the engine in situ; they had to be placed in the holes in the inner wings first then the engine installed and finally bolted up. Make sure the manifold flange and boltholes actually align with the head before you install the engine, mine didn’t and it was a real pain using jacks, wedges and blocks of wood to get it to fit.

Geoff
Geoff King

Geoff, Thanks? for cheering me up re installation of manifolds. Chris@octarine-services cut his downpipes and sleeved them to get around the problem, i think ill go down that road. I'm not going to the hassle of lifting engine out if i can possibly avoid it! I'm also concerned that Bhive havent got their quality control sorted yet re alignment of manifold bolt holes! Although the system is cheaper than others we're still talking four hundred quid.
Danny

I,ve just carried out the conversion from block hugging manaifolds to RV8 headers-made even more difficult by the proximity of the upper wishbones of my ron hopkinson handling kit and plastic wheelarch liners. I hope this doesn,t sound too jammy but I,m road testing this lot by driving 900+ miles to Lake Garda in Italy and back from the UK for my holidays.....
(Im writing this from a hotel on Lake Como..)

My friend Les Cole bought the reinforcing rings and found that they did not neccessarily give the best positon for the holes. I too was concerned about the loss of strengh to the inner wings and added flanges like ears and 6mm wire to reinforce the edges of the holes and shield the brake pipes. Thw wheel arch is a low pressure area so hot air should be drawn out from the holes. The car has generally remained pretty cool despite some warm weather and provocation from an expanding throttle cable outer sheath which had it idling at some 1500 rpm when under bonnet heat rose in a traffic jam......
I went one step further and made the holes bigger so that I could use studs rather that bolts which give much better clamping and location for the manifolds. They can be removed without taking anything off the engine.
One thing you will notice is that one side projects more than the other-on full lock the drivers side tyre will just rub the side of the manifold collector(195x65 tyres on 6x14J). This is confirmed by the differnce in distance of the down pipes from the side of the chassis rail. I used binx nuts on the studs to give high temperature locking-so far so good-I,ll confirm this when I get home....
I think the car defintely has more mid range pick up-I can,t confirm this until I get it onto a rolling road when I get back....


Best regards

John Bourke

John Bourke

John,
Your tire rubbing issue is exactly why I built my heads in a row like I did rather than in a "4 pack" like the RV8. I have at MIN 1/2" at tightest point of full lock and suspension travel..

Larry Embrey

Just had an awful thought, what do the insurance companies think of home made alterations to car body. They are usually wanting engineers reports etc. if you,ve changed the smallest item,never mind cutting chunks out of the inner wings.
Danny

Danny, it's a 'modification to MG RV8 specification' therefore should cause no problem.
David

My conversion was carried out with the engine in place but I had to remove the starter motor - difficult to remove with the old block huggers in place, but a joy to replace with the new headers - the brake vacuum servo reservoir, and the steering column. I agree with John Bourke that the re-inforcement flanges are not a reliable guide to positioning as exact position varies with each installation.

Once again there is no rubbing issue with 195x65 tyres on 7" rims with 30 offset.
Marc

This thread was discussed between 13/09/2002 and 19/09/2002

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