Huge Flatspot.

[Bedford126]

Have a customer with a cnc'd Rallye head. High comp pistons, rallye inlet and rallye ecu with the Rallye loom The car runs fine on the standard vtr cast iron mani (The 4-2-1 that came with the car had rusted through hence the standard vtr mani) But as soon as we fitted a raceland mani on it there is a massive flatspot between 2-3k rpm like the car has no power at all. Surely a manifold can't make that much difference. Any advice to what to do to get over it or any advice at all would be good. cheers.

[gazza808]

Has it been mapped?

I ask because if it's got high comp pistons etc might be running lean an pulling timing out hence huge flat spot.

[Quick]

How was it with the stock one? Refit it to see how it runs with that one!

[Bedford126]

Has it been mapped?

I ask because if it's got high comp pistons etc might be running lean an pulling timing out hence huge flat spot.

Yes mate it got mapped but we had a call to the place that mapped it and he said it was mapped with a piper 4-2-1 so shouldn't be a problem.

How was it with the stock one? Refit it to see how it runs with that one!

Runs fine with the stock cast iron one mate. Refitted it and runs fine no flat spot.

[Ross]

Have a customer with a cnc'd Rallye head. High comp pistons, rallye inlet and rallye ecu with the Rallye loom The car runs fine on the standard vtr cast iron mani (The 4-2-1 that came with the car had rusted through hence the standard vtr mani) But as soon as we fitted a raceland mani on it there is a massive flatspot between 2-3k rpm like the car has no power at all. Surely a manifold can't make that much difference. Any advice to what to do to get over it or any advice at all would be good. cheers.

Unfortunately this doesn't help fix the issue, but there's a major source of problems right there... :(

I can't assist I'm afraid mate, but CNC heads are pretty shite tbf - I hope that' not what is causing it.

[Bedford126]

Unfortunately this doesn't help fix the issue, but there's a major source of problems right there... :(

I can't assist I'm afraid mate, but CNC heads are pretty shite tbf - I hope that' not what is causing it.

Right ross. I thought this too do you mean the company cnc or do you mean the actual machining cnc because this head was done by a company called Ruskin engineering.

I'm hoping its not a issue with the head because I plan on buying the car later this year. Lol....

[Ross]

Right ross. I thought this too do you mean the company cnc or do you mean the actual machining cnc because this head was done by a company called Ruskin engineering.

I'm hoping its not a issue with the head because I plan on buying the car later this year. Lol....

I mean the company called "CNC Heads" - sorry for any confusion - I interpreted your post to mean it was done by them. Ignore me :p

I don't like the concept of any head being done by CNC though, simply because you can't make one head good from a template of the last head you did that was ok - no two heads came off the production line the same! Your mileage may vary of course. :)

[Bedford126]

I mean the company called "CNC Heads" - sorry for any confusion - I interpreted your post to mean it was done by them. Ignore me :p

I don't like the concept of any head being done by CNC though, simply because you can't make one head good from a template of the last head you did that was ok - no two heads came off the production line the same! Your mileage may vary of course. :)

Yeah wouldn't have been my choice but its worth thinking about if that is the problem. We will be trying a friends piper on the car tomorrow to see if that solve's the problem if not I'm baffled.

[Ross]

Have you stuck AFR on it to see what's going on?

[Bedford126]

Have you stuck AFR on it to see what's going on?

yeah and had it plugged in no faults shown. fuel and air seem fine. Its almost like there is a blockage in the 4-2-1 if that makes sense.

[Ross]

it shows its fine even with that flatspot?? How fucking bizarre.

[Bedford126]

it shows its fine even with that flatspot?? How fucking bizarre.

yup exactly my problem.

[jones91]

No sensors accidentaly pulled out when swapping them over? And no damage or dents on the manifold either?

[Bedford126]

We found the problem with the Raceland bought from ebay. If any one can tell me why or what this does or what its for would help me have faith in the human race.

We fitted the piper and no problems. So deciced to swap the lambda sensors over and after removing the one from the ebay raceland we found this.... problem solved.

Its made from a thin aluminium and when its fitted it sort of makes a ramp to the lambda. I have no idea what the crank who did this was thinking at all.
http://i50.tinypic.com/111i60z.jpg

[Daz_Kez]

LOL now that's a contraption and a half..
Some new go faster mod? Ahahaha..

[stupotvtr]

We found the problem with the Raceland bought from ebay. If any one can tell me why or what this does or what its for would help me have faith in the human race.

We fitted the piper and no problems. So deciced to swap the lambda sensors over and after removing the one from the ebay raceland we found this.... problem solved.

Its made from a thin aluminium and when its fitted it sort of makes a ramp to the lambda. I have no idea what the crank who did this was thinking at all.
http://i50.tinypic.com/111i60z.jpg

Some idiot think they were making a butterfly valve for the exhaust??

[jones91]

Wtf?? That's probably the most retarded mod I've seen in a long time!!

[Gandi699]

so they'd have had to drop that up inside the manifold til it gets to the hole and then screw it in? Bet you were glad when you found it!

[Bedford126]

so they'd have had to drop that up inside the manifold til it gets to the hole and then screw it in? Bet you were glad when you found it!

Yea looks like it mate we unscrewed the lambda and that fell out the pipe it's quite honestly pissed me off all weekend.

[saxdazza]

thats some strange contraption...

on another note.. you cant get much better than a CNC'd head. its not done as a template by the previous head. 1 inlet port and 1 exhaust port are developed and gas flowed until they cant be made to flow any better! both the ports are then scanned and written into a program which a machine will carry out accross however many ports there are on the head. each port is as identical as the next. £thousands doesent get spent developing this kind of set up for the fun of it.

[stevo67]

I`ve never seen anything like that,i`d like to know the thinking behind that 1.

[gazza808]

thats some strange contraption...

on another note.. you cant get much better than a CNC'd head. its not done as a template by the previous head. 1 inlet port and 1 exhaust port are developed and gas flowed until they cant be made to flow any better! both the ports are then scanned and written into a program which a machine will carry out accross however many ports there are on the head. each port is as identical as the next. £thousands doesent get spent developing this kind of set up for the fun of it.

No one casting are the same,
And you'd be wrong in thinking they'll be identical an it's physically impossible for the machine to get to probably 30percent of the port so they are hand finished.

[saxdazza]

No one casting are the same,
And you'd be wrong in thinking they'll be identical an it's physically impossible for the machine to get to probably 30percent of the port so they are hand finished.

i know what your saying about the castings not been identical but youd be suprised how close most are.. would say 95% of the heads i machine the ports are 100% touched by the tools that are used. undercut tools used to blend the short turns ect so hand finishing is minimal! also each head has its figures set for the machine to know whats where.