jad Posted July 11, 2014 Share Posted July 11, 2014 Hi guys. Just doing some dreaming and thinking about options for the future. In my TVR I have a 4L serpentine "High Compression" engine. If I want to go bigger is it possible to use a 4.6 block, crank and rods and then bolt everything from the 4L to it? Would I need to use the TVR pistons for any valve cutouts or use the 4.6 pistons as well? Is there anything you cant use? On the software side of things it would obviously be beneficial to use megasquirt but is it possible to use the 4L ECU with a 4.6 Block? Just looking for peoples opinions as my experience/knowledge of the V8's is lacking a little. Cheers Jad Quote Link to comment Share on other sites More sharing options...
elbekko Posted July 11, 2014 Share Posted July 11, 2014 Which 4L ECU do you have? If it's a GEMS, you can just tell it it's a 4.6. Not sure for the Bosch. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 11, 2014 Share Posted July 11, 2014 Is the TVR a 4 litre (P38 type cross-bolted) or a 3.9? Quote Link to comment Share on other sites More sharing options...
jad Posted July 11, 2014 Author Share Posted July 11, 2014 Its a GEMS. Not sure if its a "3.9" or "4L" is there an easy way to tell? It has a serpentine belt and a dizzy. Could it possibly be a crossover point? The vehicles is from early February 1995. Cheers Jad Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 11, 2014 Share Posted July 11, 2014 The later blocks are cross-bolted, with various other changes too. I'd just fish a complete 4.6 out of a P38 and drop it in with megasquirt. Quote Link to comment Share on other sites More sharing options...
garrycol Posted July 12, 2014 Share Posted July 12, 2014 If you have a 4.0 rather than a 3.9 you can just put the 4.6 crank and rods into your 4.0 block - they are the same. You can use your 4.0 Hi Comp pistons but your compression ratio will be very high. Probably something like 11.3:1. The 4.0 pistons have less dish (volume) in them than the equivalent 4.6 pistons. I did the above with my 4.0 block and used the standard 4.0 lo comp pistons (rather than the 4.6 pistons) which give a compression ratio of about 9.2:1 in a 4.6. Garry Quote Link to comment Share on other sites More sharing options...
discomark10 Posted July 12, 2014 Share Posted July 12, 2014 I'm looking to do this. I know a guy who has a 4.0 and 4.6 with a duff liner. Is it worth running high comp over std? Quote Link to comment Share on other sites More sharing options...
jad Posted July 12, 2014 Author Share Posted July 12, 2014 Cheers guys. You say there are many differences in 3.9/4L. Can you see any from the outside? Or tell from the engine number? I'm about to crawl under it so can have a look. 11.3CR sounds a bit too high even running on 87 plus. What do you think? Guessing i would have to regard the timing somewhat? I would like the engine to have more power and rev well. May have hit the limiter a few times now as it sounds like it wants to keep on going!!! Cheers Jad Quote Link to comment Share on other sites More sharing options...
garrycol Posted July 12, 2014 Share Posted July 12, 2014 Cheers guys. You say there are many differences in 3.9/4L. Can you see any from the outside? Or tell from the engine number? I'm about to crawl under it so can have a look. 11.3CR sounds a bit too high even running on 87 plus. What do you think? Guessing i would have to regard the timing somewhat? I would like the engine to have more power and rev well. May have hit the limiter a few times now as it sounds like it wants to keep on going!!! Cheers Jad If there are side bolts on the mains then it is a 4.0 - these are visible around the bottom of the block from the outside. If the castings are there but not drilled then it is a 3.9. I was just highlighting that you can use the pistons you already have if you wanted but highlighting it would be very hi comp. You can use 4.6 Hi Comp or Low Comp pistons or 4.0 Low comp pistons as an alternative. Quote Link to comment Share on other sites More sharing options...
garrycol Posted July 12, 2014 Share Posted July 12, 2014 Is it worth running high comp over std? More power but you will need to run higher octane fuel. Quote Link to comment Share on other sites More sharing options...
ajh Posted July 12, 2014 Share Posted July 12, 2014 Are there not also stroker bits you can toss in at the same time? Quote Link to comment Share on other sites More sharing options...
elbekko Posted July 12, 2014 Share Posted July 12, 2014 If it's a GEMS, it's a 4.0. Quote Link to comment Share on other sites More sharing options...
jad Posted July 12, 2014 Author Share Posted July 12, 2014 Is it as simple as this? http://www.roverparts.com/TechTips/boschvsgems.cfm Or am I assuming too much? Didnt look at my engine when i was under it... and you cant see much from the top! Is this part of the block with no bolt for the mains mean its a 3.9? If I was to up the CR to 11.3 is there an easy way to calculate what the timing should be to allow it to run on 97+ octane? I know TVR was a bit different to LR on the timing front. Im sure there are some very knowledgeable people out there that can estimate these things.... Cheers Jad Quote Link to comment Share on other sites More sharing options...
ajh Posted July 12, 2014 Share Posted July 12, 2014 Have you considered using Megasquirt? Then you could get realtime information and program things on the dyno. Quote Link to comment Share on other sites More sharing options...
jad Posted July 12, 2014 Author Share Posted July 12, 2014 Megasquirt is definitely an option. Its going on my other project soon. Really would like to get the engine running on that! I assume using that you can set the timing to whatever you want? Will start reading up on it more soon! Its a shame the RV8 doesnt have knock sensors..... and stroker kits are out as its loadsa wonga! Jad Quote Link to comment Share on other sites More sharing options...
jad Posted July 13, 2014 Author Share Posted July 13, 2014 Can someone correct please if I am wrong... If I but a 4.6 block and heads, get it top hatted and use my 4L pistons and a composite head gaskets with the 4.6 crank and rods then I should be onto a CR of about 10.3-10.8 which should be useable. I can then either use the TVR or 4.6 heads on top and the serp front off the 4L engine. With a bit of megasquirt everything should come up rosy right? Cheers Jad Quote Link to comment Share on other sites More sharing options...
elbekko Posted July 13, 2014 Share Posted July 13, 2014 Megasquirt is definitely an option. Its going on my other project soon. Really would like to get the engine running on that! I assume using that you can set the timing to whatever you want? Will start reading up on it more soon! Its a shame the RV8 doesnt have knock sensors..... and stroker kits are out as its loadsa wonga! Jad GEMS and Bosch have knock sensors But the general consensus seems to be that it's too hard to calibrate them. Quote Link to comment Share on other sites More sharing options...
jad Posted July 13, 2014 Author Share Posted July 13, 2014 All I heard was its possible..... Funny I know some people at work in calibration. Wonder if there are any old boys about that worked on the Rover V8... and if not some of the current ones may be very helpful I feel Ta Jad Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 14, 2014 Share Posted July 14, 2014 Knock sensing is quite an art, the 4.0/4.6 had knock sensors so you're 50% of the way there, and Megasquirt can make use of them, but a knock sensor is basically a tuned microphone so there's a fair bit of magic to be performed to distinguish a knock from all the other noises going on inside an engine. I have to admit I haven't looked at the progress with MS for a long time so it may be fully working on MS3 by now, but MS3 is IMHO way more complex than you need and as long as you're sensible about tuning it you don't need the knock sensors anyway. MS1 + EDIS is plenty good enough, simple to set up and proven & reliable. Quote Link to comment Share on other sites More sharing options...
jad Posted July 14, 2014 Author Share Posted July 14, 2014 Does it help I work in NVH then? We are gonna be putting MS2 on my 1uzfe. So Im sure that will have its own complexities. Someone somewhere must have got it working..... Ill have a chat with some people and see what they say. It may help that my dads a programmer as well. Can anyone tell me if the way I am planning to build the engine will actually work?... Cheers Jad Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.