33 replies to this topic

[gsi marc]

Hi could anyone tell me if the 3.0 straight six senator engine fits the manta has ive been offerd a good low milage auto engine, If so wonderd witch box you would use, thanks

[Retro Power]

Yes it does fit, but its very heavy and will not help the handling one bit!

It will fit the std manta 2.0 GTE gearbox

[manta3000]

my manta was fitted with  24v,taken it out,16v going in
24v best in my carlton gsi

[gsi marc]

Retro Power, on 19 January 2012 - 07:52 PM, said:

Yes it does fit, but its very heavy and will not help the handling one bit!

It will fit the std manta 2.0 GTE gearbox

Thanks for that thought it might be a touch heavy, maybe a 2.0 omiga and use the engine and box then

manta3000, on 19 January 2012 - 08:03 PM, said:

my manta was fitted with  24v,taken it out,16v going in
24v best in my carlton gsi

Yes its probably going to be omiga 2.0 engine and box swap then sounds like the 3.0 litre will mess with the handling thanks

[mantadoc]

The 12V 3.0 180 BHP for a couple of hundred quid is a quick easy conversion and with decent coils under the front and doing it properly (that means not lowering the anti roll bar) it handls fine, you feel the weigh but instead of understeer use the power to use oversteer to balance it up.

Done two for a couple of mates of mine and both enjoyed driving them and didn't find the handling an issue.

[MANTAMAN]

striaght six's can be made to work very well in a Manta if the Haverinan brothers in Finland are anything to go by.....



In the race footage they have handicapped the yellow manta by making it start way back off the grid yet the only it doesn't pass is the sound barrier!!

[mantasrme]

The 12v 6cylinder is a cheap conversion and a decent power hike over the GT/e lump.
But its almost twice the weight of a 16v engine
2/3rds of that extra weight is sat infront of where the 16v fits, so it will never handle as well as a 16valved manta no mater what you do to the suspension.

As Mantaman's video shows you can get a shed load of power from a 6cylinder, but they are no where near standard engines.
Not sure what's been done to them but i'd guess there not just 3litres any more and i saw individual throttle bodies under the bonnet.

Also did you notice they'd moved the engine back into the bulkhead to get a better weight ballance and handling

[Jason b]

I've done it (well, I currently use the 2.5 but have a 3.0L engine build in the garage) and don't regret it one bit - however, as I have found, if you intend to do it properly then don't expect to be able to cheaply rebuild the 12v 6pot CIH lump - the parts seem to be very very hard to come by at sensible prices.

If you just want a fast great handling manta then there are loads of engines you can fit. I however wanted my cav to be a "what if vauxhall had made a factory straight 6 cavalier" type of build to use as a daily. That said, I have yet to redo everything properly (when the new engine drops in) but the car does handle nice and predictably as said above - it is nose heavy, but the extra grunt from even my underperforming 2.5L engine balances it out quite well. That is using ~450lb springs on the front and GAZ dampers all round...

and yes, the video above shows how well it can work, however that is not a straight drop in! - the engine is sat back a very very long way.

Edited by Jason b, 21 January 2012 - 11:20 AM.

[mantadoc]

mantasrme, on 21 January 2012 - 09:53 AM, said:

The 12v 6cylinder is a cheap conversion and a decent power hike over the GT/e lump.
But its almost twice the weight of a 16v engine
2/3rds of that extra weight is sat infront of where the 16v fits, so it will never handle as well as a 16valved manta no mater what you do to the suspension.

True, but compared to upgrading a GTE the engine is about a third heavier and the two cylinders in front of the original line probably don't shift the car's centre of gravity further forward by more than an inch or so.

Weld a Vectra B battery tray down in the boot and move your battery rearwards (consider acquiring the battery lead and terminals of a 6  cyl E36 to locate your battery in the boot) to balance it out  a bit maybe.

[monzta]

mantadoc, on 21 January 2012 - 12:38 PM, said:

Weld a Vectra B battery tray down in the boot and move your battery rearwards (consider acquiring the battery lead and terminals of a 6  cyl E36 to locate your battery in the boot) to balance it out  a bit maybe.

Yes it would, and you can make further tweaks to improve the weight balance of the car.

I too have made a couple of theese builds and there are some things to consider.

First you need to take a good hard long look at the A series TE2800 that was made in a very limited edition. When they finished the car it weighed in 200kg more than a stock GTE but it had the same weight balance as a GTE. I know of at least one user in here that drives a TE2800 for rally so maybe he can give you some tips as well

Secondly you need to stop thinking that the goldtop weighs like 2 tonnes more than everything else. It is true that it is twice as heavy as a redtop, but the redtop is a light little engine in comparison to the stock CIH anyways, so no comparisons there. The goldtop does not weigh 1/3rd more than the stock CIH. A stock 2,0GTE engine weigh in at 155kg and a 3,0E  
is 200kg, but as you dont need the 12kg servo pump you can save this weight. A C30SE 24v is only 180kg!

All in all only 40 something kg more. Yes this sits beyond the front axle but relocating the battery, removing sheet metal from behind the front bumper (on a GTE you can remove alot without it showing), and fitting fibre glass parts where available (frontwings, hood) will give you something very similar to the stock weight distribution of the car.

You do however need to upgrade your front suspension with high torsion springs, and some really good shocks. What you don´t want is a flatout as this will make your car handle crazy...

It is 100% doable, and not something that i would be affraid to do. Fair enough, you cannot get as good handling as with a 4 cyl, but you get 180bhp and 280nm´s and the C30NE is a very tunable engine. 250+ hp with good old fashioned tuning is quite possible even on a budget (camshaft, upgraded injection or open carbs)..

My old Monza had 220hp just by fitting tripple open dellorto carbs and a dual 2" exhaust system on a stock C30NE.

[mantadoc]

What he said.


All I will add to the above is that I may or may not remember someone in a 16V Nova attempting to pass my mate's 3.0 Manta  and the Nova running out of gears and dissappearing behind..


My mate's 3.0 engine cost £100, bits and bobs to fit it cost about another £100. Where do you get to upgrade a Manta to around 180BHP for £200?
Started Friday afternoon, running Saturday morning and he drove to work in it Sunday night.


Make a big wing sump tank, do not lower the anti-roll bar

Consider joining the club for a load of engine conversion resources in the members area. However if you just search this section for the words sump ,mount and pipe you will get three matches. 2 give all the info you need for a 12V

[mantasrme]

I do agree the cost of going to a 3.0 12v is about the most cost effective way of getting more power in a 2.0 GT/e engined car.
A couple of hundred quid (assuming you have the ability to do the conversion yourself and not pay someone to do it)
You're not going to get much extra power from a 4cyl cih for that sort of money.
My old GT/e had oversize pistons,a big vavle head, fast road cam, vernier pulley and a tweeked injection system and only gave 150bhp, to buy and fit that sort of stuff new would be best part of £1000

The 16v route does cost much more to do with current prices of THOSE PARTS and you're looking at around £1000 for the gear to do it (unless you have a 1.8 manta to start with )

But the c20xe weighs around 107kg thats 48kg less than a 4cyl cih, 73kg less than a 24v 6cyl and 93kg less than a12v 6cyl
For a weight comparison of the XE against a 12v 6cylinder its like having a 14.5 stone bloke sat in the front of the engine bay

I did a c30se 24v conversion recently for someone and when i fitted the engine and put the car back on the ground the back end of the car sat a couple of inches higher than it had without the engine in

[mantadoc]

mantasrme, on 22 January 2012 - 10:07 AM, said:

For a weight comparison of the XE against a 12v 6cylinder its like having a 14.5 stone bloke sat in the front of the engine bay

So there you have it, leave a mate at home  to break even with with a 16V, get him to sit in the 16V for a power to weight advantage

[gsi marc]

Thanks guys really torn now on this conversion, If i do go for it what else will i need from the senator. what about wiring ecu etc has the engines still running in the car so i can get everything in one go would be fitting to an already injected 2.0 litre Thanks marc

Edited by gsi marc, 22 January 2012 - 11:53 AM.

[opel2000]

Always a fan of the straight 6 for and against topics.

Myself I always wonder why they stopped putting the straight 6 into modern cars...... Hmm replaced by modern lighter engines at a guess.

Straight 6's though are generally lovely smooth torquey lumps, but If I was going to the hassle of doing a stright 6 it would definately be a Skyline straight 6, would never contemplate the GM unit for one minute and definately not the GM 2.5 lump.

Would also go to say....
Handling
Laws of physics simply dictate that to change the given mass moving in a certain direction will take X amount of effort
To change the direction of more mass moving in a certain direction will take more effort.
Ok so springs are designed to absorb cornering energy amongst other things but, I simply and totally refuse to believe that the laws of physics do not exist in straight 6 engined Manta's.  Handling must suffer.
But then again if I had gone to the time effort and expense of fitting one I I may possibly tell a bit of a porky and say "NAH!,,,, Nah!,,,,, NAH! handling is spot on Mate!"

Love the comments on the youtube clip "look how fast a straight 6 can go" Throw enough cash at any engine and it will go well, throw a little cash at the right engine and it will go well too is my argument, approx £800 thrown at my old 200SX (1.8 engine) would have seen 250 bhp and that is a well known conservative figure on these 1.8 engines. Superb tiny little lightweight lump approx half the weight and size of the GM straight 6

There are good modern lightweight extremely tuneable superb modern engines with plentiful parts out there, and there are old pig iron lumps that are hard to source parts for out there too, that "may not" enhance the superb handling of the Manta.

Edited by opel2000, 22 January 2012 - 01:41 PM.

[opel2000]

gsi marc, on 22 January 2012 - 11:52 AM, said:

Thanks guys really torn now on this conversion, If i do go for it what else will i need from the senator. what about wiring ecu etc has the engines still running in the car so i can get everything in one go would be fitting to an already injected 2.0 litre Thanks marc

I understand that if the Senator is an auto it is a nightmare to wire up as the ECU talks to the Autobox ECU

[doveyte2800]

Hi,
I think that most of the pros and cons have been covered by others but as one who has built and rallied a 6 cyl. Manta A in the historic rally championship can I add a word. Yes you can get a reasonable priced 3.0lt but improving it still costs money and to get it to fit and handle right takes time. Ideally you should move the engine back, around 200mm is possible but you have to modify the bulkhead and gearbox /gear lever positions ( A series, not sure if B engine bays are bigger.) new engine mounts need fabricating and the sump needs to be a reverse hand so that the deep part sits behind the crossmember. You need a bigger radiator as they do get warm but space is limited even when the engine is moved back. The battery needs to be in the boot and you may have to modify the heater area of the bulkhead. Springs need to be 300 - 400lb with a length of around 290mm, dont go too hard or your teeth will fall out, the rear spring height may need reducing to get the car sitting level. What ever you do dont forget to uprate your brakes! dont know much about electrics/injection as ours ran on Webers.
Personally i would now go for a big bore 4 cyl CIH, pick up an old 2.4 Frontera, use the engine and scrap the rest ( £300 for car, £220  weigh in so £80 for engine) as it sits in the same place as the original engine and has plenty of grunt and can be easily modified.
Anyway good luck whichever way u go
Ian

[opel2000]

Thankyou Ian, superb post.

[gsi marc]

Yes ian i can see your point thats why i posted the topic so i could se what the guys on here had to say. Must be honest i hadnt really thought much about a frontera motor but looks like it would be a damn sight easier conversion on a budget. Like most of the guys on here have said the straight six seems to be a step backwords so back to the drawing board on this, Time to look at the frontera motor then and whats involved, Thanks to everyone for the input on this,,,, marc

[monzta]

Regarding the Frontera engine (its also to be had from some Carltons by the way) it is very underpowered when it comes stock. The injection system is the big sinner here, as its the only CIH to be made running with the new bosch injection similar to the one on the 16V. Also intake manifold is very small and the throttle body has a bottle neck like you´ve never seen before. As stock it only produce 125hp, but they are SO tunable you wouldnt believe it. But if you want to get that hidden power you will need to scrap the fuel injection. No CIH engine will take good power gains running the Fuel injection system that was fitted from the factory. Twin carbs is the only way to go, unless you can get your hands on some open throttle bodies wich will be the best you can do (give you a decent mpg as well).

Fit a 2,5" exhaust system to a 2,4 and a set of twin carbs and you will have 150bhp. Add a camshaft and you will have 170 or more.

I must say however, that even though handling will suffer a bit it won´t be undrivable. Look at Porsche 911. There´s a car that has got the laws of physics upside down but they are still racing the blody things around every racetrack in the world..

My point is, that the fact of the matter is that you will not get cheaper power gains than a straight 6. The C30NE is not even a slow 6, its fast reving and very very sporty to drive. That engine is by my opinion the best 2 valve pr cyl CIH ever made .. Further power gains are easy to get, and breaking the 200hp mark is extremly easy and cheap. Getting a 16V or a 2,4 above 200hp (even getting them to reach the 180hp) will cost you what 3 whole C30NE engines will cost..

The downsides are the heavy front end, but as said, there is alot you can do about it. When moving the battery to the trunk you actually removes twice the weight of the battery as the weight now rests on the rear axle. Removing sheet metal parts of the front end will also save you some weight, especially the front panels behind the front bumper apron will be a good thing to remove. Getting the right springs and shocks will further make the issue seem alot more reasonable. And last but not least, learning to know your car after the build will give you the last edge. It will not handle like a 4 cyl Manta anymore, but when you know the car, and its limitations, i am quite confident that you will never be sorry about a 6 cyl conversion.

As stated before, i would not hesitate if it was me