Turbocharging 4.0 Serpentine Chimaera?
Discussion
Idling some time away in the classifieds I spied a Janspeed turbo for sale (says "suitable for Rover V8 subject to jiggling" or words to that effect).
Just wondering how big a job this might be and what else would need doing to make it run properly (mapping etc).
Would it be safe on a 43,000 mile engine?
Piece of string question, how much extra bhp/torque could you expect running at a reasonable level of boost?
What's a 'reasonable level' of boost?
Could you still run it as an everyday car?
Do I have too much time on my hands, should I get off the interweb and go outside?
Anyone care to humour me?
Just wondering how big a job this might be and what else would need doing to make it run properly (mapping etc).
Would it be safe on a 43,000 mile engine?
Piece of string question, how much extra bhp/torque could you expect running at a reasonable level of boost?
What's a 'reasonable level' of boost?
Could you still run it as an everyday car?
Do I have too much time on my hands, should I get off the interweb and go outside?
Anyone care to humour me?
To install a turbo would be a pain in the ass, it would be simpler to install a supercharger.
you need to; construct new inlet and exhaust routes through the turbo, install the cooling lines for turbo, sort out the fuelling, lower the intake temperature, possibly change the bottom end to reduce the compression, the list goes on........
How much power would it make ? ...... how much money do you want to spend ?
you need to; construct new inlet and exhaust routes through the turbo, install the cooling lines for turbo, sort out the fuelling, lower the intake temperature, possibly change the bottom end to reduce the compression, the list goes on........
How much power would it make ? ...... how much money do you want to spend ?
I suspect that no standard RV8 turbo manifold is going to clear those chassis rails so you'd be looking at a custom fabrication. $$$
Apart from that it's nothing that large amounts of time and money couldn't solve. On the other hand you could get double your current power output for rather less money using tried and tested NA technology.
Apart from that it's nothing that large amounts of time and money couldn't solve. On the other hand you could get double your current power output for rather less money using tried and tested NA technology.
as above doubt the JS manfolds would fit, your main problem will be heat 
inlet side is easy, you'd need custom manifolds which is the main stumbling block...
43k engine i thing fine at reasonable boost, reasonable boost being 6-9psi.
powerwise probably 30-50% extra both bhp & torque
you'd also need a method of adding more fuel and retarding the ignition while on boost - nothing a fully mapable ecu can't do
perfectly feasible IMO all comes down to £££ like everything else
inlet side is easy, you'd need custom manifolds which is the main stumbling block...
43k engine i thing fine at reasonable boost, reasonable boost being 6-9psi.
powerwise probably 30-50% extra both bhp & torque
you'd also need a method of adding more fuel and retarding the ignition while on boost - nothing a fully mapable ecu can't do
perfectly feasible IMO all comes down to £££ like everything else
You need to use a forward mounted single turbo fed by both banks of headers. I cast twin turbo manifolds which are similar, well better then the janspeed manifolds. Problem is, they may foul the chassis rails.
A simple turbo install is very viable on a stock engine.
Boosted.
Thinking more about this I could cast a special manifold and move the turbo to a suitable location. It's definately a really good way to power and big easy torque. Did it on my 4.5 and 5.1 and you can keep it simple (read low cost).
>> Edited by Boosted LS1 on Thursday 23 June 21:22
A simple turbo install is very viable on a stock engine.
Boosted.
Thinking more about this I could cast a special manifold and move the turbo to a suitable location. It's definately a really good way to power and big easy torque. Did it on my 4.5 and 5.1 and you can keep it simple (read low cost).
>> Edited by Boosted LS1 on Thursday 23 June 21:22
mmm you've got me thinking now...there is a fair bit of room in the Tuscan engine bay,
now the exhaust system on the tuscan is a pair of zertec headers going forward, then two custom pipes going to the side mount original tuscan exhaust.
ok so how feasible would it be to make a second set of the intermidiate pipes and plum in a turbo. a nice small one with only a mild amount of boost.
would it be possible to run the engine in 2 different configurations.. no turbo and the original pipes for the TVRCC races, and then bolt on the turbo if i wanted to do anything else..
any comments? possible or daft idea
G
now the exhaust system on the tuscan is a pair of zertec headers going forward, then two custom pipes going to the side mount original tuscan exhaust.
ok so how feasible would it be to make a second set of the intermidiate pipes and plum in a turbo. a nice small one with only a mild amount of boost.
would it be possible to run the engine in 2 different configurations.. no turbo and the original pipes for the TVRCC races, and then bolt on the turbo if i wanted to do anything else..
any comments? possible or daft idea
G
Would it be sensible to drop the compression ratio if you're planning to run as much as 5-7 psi of boost? I've found that even with a nominal cr as high as 10:1 it is possible to run 6 psi without detonation by running very rich, chucking in loads of water and backing the timing off. But I suspect that you would be able to achieve more power from the same boost by dropping the CR and removing the excess fuel and ignition retard? I'm going to try 8.5:1 and see how that works.
Well, if you leave the machanicals as they are then the engine will perform like an atmo unit and give good fuel returns and throttle responsiveness off boost. Then it will take off when the boost kicks in. In a way it's like getting the best of both set ups.
It's not easy to lower the compression in a cost effective manner. I don't like thick gaskets so it has to be fresh pistons for me or bigger combustion chambers. The engine could be boosted in it's current state. I could hold 7 psi all day if the road would allow it! It would peak at 10 psi on gear changes but I could never make the engine accept more then 7-8 psi sustained boost.
Boosted.
It's not easy to lower the compression in a cost effective manner. I don't like thick gaskets so it has to be fresh pistons for me or bigger combustion chambers. The engine could be boosted in it's current state. I could hold 7 psi all day if the road would allow it! It would peak at 10 psi on gear changes but I could never make the engine accept more then 7-8 psi sustained boost.
Boosted.
I'm not sure how safe it is to run that much boost without lowering the CR, I had to run a lot of excess fuel, water and ignition retard to avoid detonation. It feels like a fragile system that is being compromised quite a long way by the need to avoid detonation.
Unfortunately in my case the base engine had already been modded to raise the CR to about 10:1 and there's very little scope to drop it again without changing the pistons (£££). The combustion chambers are already quite big and not much meat to open them up, not much scope to take volume out of the pistons, head gasket is already the thick composite type and I've been advised 60 thou is about the max that thickness that can be used reliably. The logical next step would be to change the pistons but this seems very expensive, and one of my goals was to stick with a cheap base engine.
The approach I'm trying now uses decompression shims to drop the CR (my target is about 8.5:1 for 6 psi boost). These are simple alluminium (or copper) plates CNC machined to match the shape of the heads, glued onto the heads with non-setting adhesive, conventional head gasket used underneath. I'll let you know how it goes, PLEASE don't tell me this is a bad idea!
Unfortunately in my case the base engine had already been modded to raise the CR to about 10:1 and there's very little scope to drop it again without changing the pistons (£££). The combustion chambers are already quite big and not much meat to open them up, not much scope to take volume out of the pistons, head gasket is already the thick composite type and I've been advised 60 thou is about the max that thickness that can be used reliably. The logical next step would be to change the pistons but this seems very expensive, and one of my goals was to stick with a cheap base engine.
The approach I'm trying now uses decompression shims to drop the CR (my target is about 8.5:1 for 6 psi boost). These are simple alluminium (or copper) plates CNC machined to match the shape of the heads, glued onto the heads with non-setting adhesive, conventional head gasket used underneath. I'll let you know how it goes, PLEASE don't tell me this is a bad idea!
Hello Peter,
Your engine started life with to high a compression in the first place which limited your boost level. It possibly prevented you from using as much as 3 psi above what you currently use. Plenty of rovers on 9:1 c/r have run using 7 odd psi and the compression didn't need lowering.
Given the package that you have, compression plates may be the only way to go but they lower compression whilst promoting detonation due to the loss of squish effect. Your engine will become less efficient at burning fuel. If this were my engine, I'd tighten the squishband by fitting thinner gaskets. You'd get a faster burn then. Later on I'd look for an export bottom end on 8:1 c/r and use that
In the real world your plates will work just fine. Another bolt on option is a pair of buick 300 alloy heads from 1963/4 with 54cc combustion chambers. They have big ports as well. Downside is the bore on a buick is 96mm (iirc), your bore is 94mm but this shouldn't be a major problem and could be modded if required. Buick has a big inlet valve but the exhausts a bit smaller, iirc. Long time since I had a pair and they usually need refurbishing!
Boosted.
Your engine started life with to high a compression in the first place which limited your boost level. It possibly prevented you from using as much as 3 psi above what you currently use. Plenty of rovers on 9:1 c/r have run using 7 odd psi and the compression didn't need lowering.
Given the package that you have, compression plates may be the only way to go but they lower compression whilst promoting detonation due to the loss of squish effect. Your engine will become less efficient at burning fuel. If this were my engine, I'd tighten the squishband by fitting thinner gaskets. You'd get a faster burn then. Later on I'd look for an export bottom end on 8:1 c/r and use that
In the real world your plates will work just fine. Another bolt on option is a pair of buick 300 alloy heads from 1963/4 with 54cc combustion chambers. They have big ports as well. Downside is the bore on a buick is 96mm (iirc), your bore is 94mm but this shouldn't be a major problem and could be modded if required. Buick has a big inlet valve but the exhausts a bit smaller, iirc. Long time since I had a pair
and they usually need refurbishing! Boosted.
Feedback from others who have tried this suggests that the strength of the little ends using the stock cast pistons is a limiting factor. I'm hoping that by dropping the compression ratio I can drop the peak cylinder pressures and hence the peak loads. I see your point about the loss of squish, I guess that fitting bigger volume heads or shorter pistons would be a better solution leading to a more efficient engine.
I'm hoping to avoid such a drastic change. I'm trying to stay as close as possible to a stock 4.6 base engine just with some fancy bits bolted on the top. It's never going to be the ultimate power setup, but I'm sure you can see the potential for a 'simple' bolt-on upgrade that gives a an extra 100 lb-ft or so of torque. It certainly makes a spectacular difference from the driver's point of view.
I'm hoping to avoid such a drastic change. I'm trying to stay as close as possible to a stock 4.6 base engine just with some fancy bits bolted on the top. It's never going to be the ultimate power setup, but I'm sure you can see the potential for a 'simple' bolt-on upgrade that gives a an extra 100 lb-ft or so of torque. It certainly makes a spectacular difference from the driver's point of view.
GreenV8S said:
If this were my engine, I'd tighten the squishband by fitting thinner gaskets.
Did I mention that the pistons were originally running 20 thou out of the top of the block?
Nice and tight on the squish then! You won't want tin gaskets. Composites will lower the compression a tad and if you get genuine tvr composites they are extra thick and have a really decent fire ring. They may be .050" .055" ish thick so you will lose compression and still retain squish effect
. Defo worth investigating! Oh, your peak cylinder pressures don't go up by to much or for more then a nanosecond but the average is higher. The pistons and little ends should be fine with low boost so long as you don't detonate and the 4.6 has unslotted pistons, more strength. Boosted.
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