LUMPY

Engines, Transmissions & Final Drive questions and answers

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wozzah1975
Fast Driver
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Joined: Sun Oct 30, 2011 11:39 pm

Re: LUMPY

Postby wozzah1975 » Thu Jan 12, 2012 5:48 pm

slimx wrote:I have a VVT model NB
And im looking for LUMPY CAMS

STAGE 2 - STAGE 3

I am aware that lumpy cams are only good for higher RPM im only getting it for the "rotary-like" sound. And im willing to put up with the cold start issues :)

WHERE DO I LOOK? VVT seems so limited when it comes to cams. I've found NONE

------
If cams are no good.. How else can i get a TAD more .. power + ROTARY sound. Without spending 10+k on a rotary conversion


You can fit "lumpy" cams, but to make them work with the VVT is a problem. The other issue with the VVT is that it is specifically designed to give power at both ends of the rev range, so in effect it makes larger cam profiles less lumpy. This will mean you need to "overcam" it to get it lumpy at all. Not a good idea.

The other issue is that with the efficiency of newer heads and management systems that big cams become less lumpy, and there is not much you can do to change that.

There are 2 options.
1.
Fit really big cams to get it "Lumpy" This will require an ECU change, valve springs, possibly larger valve reliefs in pistons, valve train beef up, then you will need someone to tune it properly, and VVT engines are harder to get right than normal engines. If you do it right, then headwork will be required, as will a higher comp ratio, and improvements to the intake (eg: throttle bodies) and extractors/exhaust. If you fit big cams without carrying out the appropriate work to go with them, then it will either be super unreliable, perform poorly, but most likely both.

2. Fit sensible cams that require not alot of mods (maybe an ecu). They won't be "lumpy", but given the right mods will make better power.

You could make it lumpy with the standard gear, just alter the cam timing and detune it. Simple. How will it perform? sh*t. Will it be lumpy? YES

Either way, there is no simple way of having it lumpy, and having it make better power at the same time. On that style of engine the 2 don't go together without spending a bucket load of money, and for a road car it would be simply not practical.

Cheers
Woz
BP DOHC Mk1 Escort race car. Big Valve head, Cosworth Cams, Spool Rods, Nissan Pistons
www.facebook.com/pages/Warren-Heath-Per ... 4779879292

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slimx
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Vehicle: NB8B - Turbo
Location: Sydney (Sth West)
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Re: LUMPY

Postby slimx » Fri Jan 13, 2012 5:52 am

Wozza if we had a "reputation" system in this forum i would give u +1 :)

Thank u for your response. and check your pm

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username
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Posts: 288
Joined: Sun Apr 18, 2010 3:58 pm
Vehicle: NA6

Re: LUMPY

Postby username » Fri Jan 13, 2012 5:10 pm

I must say...this just sounds freaking awesome

http://www.youtube.com/watch?v=n5S4uNtgJQ8
"signatures - a good place for a list of your cars modifications" -Jace

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Russellb
RIP Nov 2014
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Vehicle: Clubman
Location: Harden NSW
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Re: LUMPY

Postby Russellb » Fri Jan 13, 2012 6:35 pm

wozzah1975 wrote:2. Fit sensible cams that require not alot of mods (maybe an ecu). They won't be "lumpy", but given the right mods will make better power.

You could make it lumpy with the standard gear, just alter the cam timing and detune it. Simple. How will it perform? sh*t. Will it be lumpy? YES

Either way, there is no simple way of having it lumpy, and having it make better power at the same time. On that style of engine the 2 don't go together without spending a bucket load of money, and for a road car it would be simply not practical.

Cheers
woz

You could fit an ECU and Run Rotational Idle
Sounds TOUGH and LUMPY not so good for Valves ECT . but no down side in performance.
So you could fit cams ECT

I have it on the Rally MX5 and Can make a Video of Idle ( i have none because it sounds better under Anti LAG)
My ClubmanRebuild
MX5 Solution Canberra ( aka carco )http://www.carco.com.au
Russell's Race and Rally Service
MX5 SE Rally car is HERE :)


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