Engine advise please....
Discussion
Didnt get much responce on the tvr major mod forum so I thought I would repost this in here. Anyone got any ideas?
The 4.0HC in my Chim has started to sound like a sewing machine so its new cam time. This winter the engine will come out and be stripped. Its the intermediate engine, so its not cross bolted but has the bosses to be so. It may or may not have the end caps for cross bolting as I haven't had the sump off yet. It will have the small journal crank shaft.
I'm after a bit more power (arn't we all!) and this seems like the prime opportunity to do it. Just one small problem, I'm moving house and the wallet emptying ability of my wife is second only to that of my car! So I'm on a budget.
I was thinking of up grading to a 4.6 small journal crank (I think JE do one) but can I use my current con rods and pistons, subject to ware? Also is it possible to get hold of some cross bolting end caps to strengthen the bottom end?
By going down the 4.6 route I wont have much to spend on the heads. Just a refresh of what is already there, so no big valves and extensive porting. Is it worth going down the 4.6 route if the heads are going to stay as standard, or am I best to stick with the 4.0 and spend the money on the heads? the engine will be stripped and overhauled anyway so I not counting that as part of the cost as it will be done no matter what happens.
The other option is to keep the 4.0 engine and get some big valve and ported heads and a a camshaft to match.
I don't do many track days so I'm not after top end power, but I do spend allot of time in traffic and on country roads. So I'm after drive-ability and torque, but I don't want it to run out of steam at 4000rpm! I don't want much, honest!
Any advise anyone can offer would be gratefully received! as I'm in a quandary at to what to do and where the money is best spent.
The 4.0HC in my Chim has started to sound like a sewing machine so its new cam time. This winter the engine will come out and be stripped. Its the intermediate engine, so its not cross bolted but has the bosses to be so. It may or may not have the end caps for cross bolting as I haven't had the sump off yet. It will have the small journal crank shaft.
I'm after a bit more power (arn't we all!) and this seems like the prime opportunity to do it. Just one small problem, I'm moving house and the wallet emptying ability of my wife is second only to that of my car! So I'm on a budget.
I was thinking of up grading to a 4.6 small journal crank (I think JE do one) but can I use my current con rods and pistons, subject to ware? Also is it possible to get hold of some cross bolting end caps to strengthen the bottom end?
By going down the 4.6 route I wont have much to spend on the heads. Just a refresh of what is already there, so no big valves and extensive porting. Is it worth going down the 4.6 route if the heads are going to stay as standard, or am I best to stick with the 4.0 and spend the money on the heads? the engine will be stripped and overhauled anyway so I not counting that as part of the cost as it will be done no matter what happens.
The other option is to keep the 4.0 engine and get some big valve and ported heads and a a camshaft to match.
I don't do many track days so I'm not after top end power, but I do spend allot of time in traffic and on country roads. So I'm after drive-ability and torque, but I don't want it to run out of steam at 4000rpm! I don't want much, honest!
Any advise anyone can offer would be gratefully received! as I'm in a quandary at to what to do and where the money is best spent.
The 4.0 and 4.6 is the same bore (94mm), so the pistons should be reusable, but you may have to change the rods to get the CR's right. You may find it difficult, expensive or both finding a 4.6 crank with the smaller bearing journals of the intermediate engine
In terms of cross bolting, it's only really needed if you plan on revving the nuts off the engine eg 7k plus, I'd save your money, or spend the money on head work, bulleted bronze valve guides maybe.
V8Developments have a new cam that seems to be very good for what your after, more power without sacrificing drivability, I've ridden as a passenger in Quinny's Griff 500 with it fitted and the car pulled like a train from idle until we ran out of road in 5th.
Regards
Iain
In terms of cross bolting, it's only really needed if you plan on revving the nuts off the engine eg 7k plus, I'd save your money, or spend the money on head work, bulleted bronze valve guides maybe.
V8Developments have a new cam that seems to be very good for what your after, more power without sacrificing drivability, I've ridden as a passenger in Quinny's Griff 500 with it fitted and the car pulled like a train from idle until we ran out of road in 5th.
Regards
Iain
My take on Matt Faulks' upgraded 4.0:
www.pistonheads.co.uk/gassing/topic.asp?t=276614&f=8&h=0
In a lightweight sports car like the Griffmaera, I'd go for upping the flow capability of the heads (incl. cam) - looking for more power further up the rev range which in turn makes for a wider useable rev band and better driveability - before enlargening the capacity - although if I had bottom end problems, I would go for a crossbolted 4.6 block in a heartbeat as well.
By going down the 4.6 route I wont have much to spend on the heads.
Remember that it's the flow capacity of the heads that ultimately determine how much power you can get - how much swept volume lies beneath merely determines the rpm levels needed to get at that power.
edited for dodgy quoting
www.pistonheads.co.uk/gassing/topic.asp?t=276614&f=8&h=0
In a lightweight sports car like the Griffmaera, I'd go for upping the flow capability of the heads (incl. cam) - looking for more power further up the rev range which in turn makes for a wider useable rev band and better driveability - before enlargening the capacity - although if I had bottom end problems, I would go for a crossbolted 4.6 block in a heartbeat as well.
jonnyb said:
By going down the 4.6 route I wont have much to spend on the heads.
Remember that it's the flow capacity of the heads that ultimately determine how much power you can get - how much swept volume lies beneath merely determines the rpm levels needed to get at that power.
edited for dodgy quoting
Edited by 900T-R on Wednesday 7th June 19:41
. Sorry for the confusion.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff