CulRidr's MP3 N/A build (~150whp goal)

depending on resistance to detonation, you can actually fill the hole somewhat with timing. Its a common thing on cars with variable cam profiles (vtec etc) to ply the hole with lots of timing to keep the curve nice and linear... the same applies to us with a single cam profile and big cams that are not that efficient in low RPM...of course you are limited in how far you can push this.

I believe I finally managed to get it right after I got over my fear of timing... but then I lost it again when I changed back to NGK platinums in the "6" heat range (equivalent of BKR6E-11s)... my settings worked fine on BKR7E-11s.

Oh well... live and learn. I'm saving up to book dyno time this weekend to finally sort it all out, once and for all...
 
I'm essentially running them as turbo cams with +/- 12 camshaft degrees for intake/exhaust, ie: 6crankshaft degrees (did I get that right?), closing most if not all of the overlap... definitely moved the powerband lower down. Not sure about how much "gid-up-and-go" I have in the earlier RPMs, but it does pull well most of the way unless I shift too early. If I do so and "land" around 2K or a shade higher, that's when I get a complete lack of power/torque until 3X00 RPMs.

Pretty sure that is 24 crankshaft degrees - i.e. crank spins at twice the rate of the cams.

Yeah, there are 12 camshaft degrees overlap difference between the Turbo and N/A Twiggy cams.

Which cam did you adjust? Or did you adjust both?
 
Pretty sure that is 24 crankshaft degrees - i.e. crank spins at twice the rate of the cams.

Yeah, there are 12 camshaft degrees overlap difference between the Turbo and N/A Twiggy cams.

Which cam did you adjust? Or did you adjust both?
I adjusted both cams equally, ie: 6 degrees each to close the overlap entirely. I had started with 3 and 3 sometime last year and although it wasn't tuned, I didn't like the large hole in the powerband so I had adjusted one more time. I can take a picture if someone is interested; they were adjusted using Focus' cam gears.
 
I adjusted both cams equally, ie: 6 degrees each to close the overlap entirely. I had started with 3 and 3 sometime last year and although it wasn't tuned, I didn't like the large hole in the powerband so I had adjusted one more time. I can take a picture if someone is interested; they were adjusted using Focus' cam gears.

Some overlap is needed, and in fact with higher compression you can afford more overlap with few ill effects (because your dynamic compression remains roughly the same).

On an NA motor, overlap feeds into the scavenging process - exhaust valve does not remain open at the beginning of the intake stroke, the scavenging wave cannot help pull air in to the motor.

I understand the desire to close the overlap on the twiggy's - they are very racey cams and it takes a bit to get them to behave especially at idle, but by closing the overlap almost completely you are going to hemorrhage power in the top end.

Reason you close it on a turbo motor is because the open exhaust valve causes you to lose boosted air being forced into the cylinders - but on an NA motor your goal is to reduce pumping loss and maximize horsepower any way you can.
 
Some overlap is needed, and in fact with higher compression you can afford more overlap with few ill effects (because your dynamic compression remains roughly the same).

On an NA motor, overlap feeds into the scavenging process - exhaust valve does not remain open at the beginning of the intake stroke, the scavenging wave cannot help pull air in to the motor.

I understand the desire to close the overlap on the twiggy's - they are very racey cams and it takes a bit to get them to behave especially at idle, but by closing the overlap almost completely you are going to hemorrhage power in the top end.

Reason you close it on a turbo motor is because the open exhaust valve causes you to lose boosted air being forced into the cylinders - but on an NA motor your goal is to reduce pumping loss and maximize horsepower any way you can.
So what's your recommendation in terms of final adjustment to the cam gears knowing that I am now essentially running "turbo twiggys", keeping in mind that it is a DD, therefore not wanting to kill too much of the low end power while limiting upper end hemorrhaging? Opening the exhaust a degree or two, or ____?
 
So what's your recommendation in terms of final adjustment to the cam gears knowing that I am now essentially running "turbo twiggys", keeping in mind that it is a DD, therefore not wanting to kill too much of the low end power while limiting upper end hemorrhaging? Opening the exhaust a degree or two, or ____?

how long is a piece of string? it really comes down to the tune, and really should be done on a dyno with back to back runs and 1 degree adjustments.

Unforunately such a thing is a little bit of a pain on the FSDE because the valve cover doubles as the top of the drive belt cover.... if it were a 4G63 or something you could run the thing without the drive belt cover on and adjust without having to pull the valve cover off.....

i'd go halfway between where you are now and where the twiggy base setting is... and retune. Then take a punt at a particular direction you think might work and make minor adjustments, retuning each time.

b**** of a job, but results should be worthwhile.
 
how long is a piece of string? it really comes down to the tune, and really should be done on a dyno with back to back runs and 1 degree adjustments.

Unforunately such a thing is a little bit of a pain on the FSDE because the valve cover doubles as the top of the drive belt cover.... if it were a 4G63 or something you could run the thing without the drive belt cover on and adjust without having to pull the valve cover off.....

i'd go halfway between where you are now and where the twiggy base setting is... and retune. Then take a punt at a particular direction you think might work and make minor adjustments, retuning each time.

b**** of a job, but results should be worthwhile.


Can't you trim back the belt cover and leave the sensor in tack thus giving enough room to make adjustments?

Edit:
Something like this...
http://i275.photobucket.com/albums/jj298/br289165/DSCN1104.jpg
 
Last edited:
Sounds like a lot of work I can't quite afford right now, but good advice nonetheless... advice I'll heed when I have the coin to afford that level of tuning. As for the cam gears, I've already cut my VC to access the adjustable cam gears; the exhaust side is a bit of a pain to adjust since the cam position sensor prevents adjusting one or two of the screws.

CopyofIMG_1747.jpg
 
I read the whole build glad to see you took the time to plan it all out and take advice. I love the build
 
So after a rather painful experience last winter with a dark curb - where I severely pinched my bottom two tubes of the header - I finally got it fixed since I now have a job again. Let me tell you that the tune definitely had a big impact because she hauls now! I'll eventually post pix of the before and after; my favourite local welder did a fantastic job!
 
Have I seriously not updated this since July? Wow...
Been a while since I've updated this, despite the car being in storage, so I'll update what I've posted on another forum.

1. The cat is pooched, so that will get replaced by a Bnez high flow one available here in the spring time: http://rx7.com/store/rx7/fcexhaust.html After doing some further reading, I'm not so convinced that the catalytic converter is finished so I'll be doing a couple of other emission related changes to see what the emission tests say before going through this fairly expensive route.
2. The primary O2 sensor is running a little erratically, so a new one needs to go in as well. This will still happen and will be part of a small order from MSM
3. Despite putting in a refreshed EGR valve, looks like I'll have to give in and get the revised model as mine is not operating properly. This and the above will be coming from MSM. eBay FTW on this one; found a revised EGR less then half of retail (brand new) and it's patiently waiting in the basement for springtime...
4. Rear lateral arm bushings are finished, and they need replacing so Megan Racing or Hardrace adjustable ones will go in giving me access to more camber, and being able to put back the stock strut bolts in and selling the Eibach ones I've been using for the past 2 years. Found a set of Megan Racing links from a TOP member and will be getting my hands on them before end of winter.
5. 2. The front lower control arm bushings are FINISHED. The control arms themselves are defective in terms of the welded nuts being snapped off for now. The plan is to buy some aftermarket OEM-like LCAs and have Pedders bushings pressed in. That will give me back the precise steering I've been missing the last few months due to those bushings slowly dying. LCAs will be part of the MSM order unless I choose to get aftermarket OEM replacements which should save a bill or two. Got an email today that Pedders bushings have finally reached my chosen distributor and I should get them fairly shortly
6. Mazdas247 is having a huge sale on chassis-stiffening gear that are copies of GTspec so that will complete the suspension rebuild; the vbraces are the only item I don't have. Received the reinforcement panel/Vbraces this past fall; looking forward to the extra stiffening it will provide
7. The kinks in the header from my incident last winter were repaired in the spring, but I still need to get it "unbent" to bring the exhaust forward an inch or so. Hopefully it can be a quick and easy job, and then it will be ceramic coated to keep the under-hood temps down. Still planning to have this done.
8. The radiator will eventually go as they all do, and the car produces a lot of heat so I found a good deal on a Ron Davis one (same one Brian has). That will go in at the same time. This one is up in the air; I won't be going down the proposed route as the person selling it has been unresponsive, and there has been a better (for me) option created by a US racer/Mishimoto. If budget allows, I'll get this in the spring, otherwise it will have to wait.
9. Finally fix my e-brake so it works properly (main cable/proportioning spring being the likely culprit) Still planning to do this.
10. Under-hood temps will be back to normal with a reverse cowl hood that will hopefully come in this month through a GB. It should look absolutely fantastic once painted. GB fell through, and savings for an out-of country trip will take precedence over this unnecessary part.

Other items...

1. The battery is starting to go. It still has decent cranking power (worked on the DD Jetta even at -30*C) but would rather get it taken care of rather then get stranded as it is down roughly 30% on CCAs. Deka Batteries makes a 15lb motorcycle battery usable in DD vehicles and I will be going this route. MMP makes a great battery box and I will therefore get the box/battery from them in the spring and adapt the box to the Proteg platform as they were originally designed to be a bolt-on for VWs.
2. Been wanting to change the pedals on the MP3 for a while for easier heel&toe and will be getting some 2003.5 pedals from the MSP through MSM. I had made this purchase in the past, but was not able to remove the covers from the pedals as the screws were completely seized and therefore sold them off. I will try again to remove them with an impact, but if that doesn't work, I have some spare pedal assemblies in the basement courtesy of John.
3. Again related to emissions, I've read that the PCV system can be a true source of horrible emission problems, while being poorly designed and feeding back gunk into the engine. Signature Sound has designed an oil catch can for me. Hopefully this will be the last piece to get emissions in check. If not, then I'll try to get that further tune before going the new cat route...
4. There are a couple more things sitting in the basement that I've been wanting to get installed for a while now, but that will have to wait for the more important things
5. Autocross tires; mine are pooched, and will be waiting for a local shop's sale prices to decide which ones to get and where I will do so.

Here is the catch can/PCV system:

CulridrTMF3.jpg
 
Last edited:
I just recently bought the Braille B2015 15lb battery with the Braille aluminum mount. I currently have the battery in the stock location laying on it's side with the battery posts mounted on the side so that they are in the same orientation as stock. The battery fits perfectly. I am planning on moving the battery to the spare tire well. The battery will fit under the carpet, but you give up the spare. There is a picture of this type setup on one of the VW forums.

Braille batteries are allegedly manufactured by Deka. Appearance wise they are identical. The Dekas are a lot less expensive than the Brailles, but I was concerned with the low CCA's of the Deka version, the Braille B2015 has 426 CCA which is not bad compared to 500 CCA of a cheap OE replacement.
 
I've read that entire thread on the Vortex, and will still go with the Deka as I highly doubt that they are any different, and the price for the battery plus awesome tray is not much more then just the Braille battery. As well, CCAs won't mean much to me since it won't be winter driven...
 
Have you dyno it?

I have a similar setting
Im running an Fp engine with;

Jspec pistons .20overbore
full work on head .80 shave
twiggys
SR camgears
626 IM
obx crankpuley
custom intake
custom exhuast
eybach valvesprings
and the best of all a 4.68 Mfactory finaldrive

I got a Megasquirt2 intaling it soon
not dyno yet
 
im planing on hiting big numbers on my n/a build...but u should really dyno it heres the parts ill be geting on this build :)

2.0l duh!
fidanza flywheel
stage 2 clutch
awr mounts
awr rad
flashed ecu
obx header
fully forged block
stage 1 speed circit headed but porting the intake and exhaust ports my self
a custom / forced induction cai
jdm cams
adj cam gears
ac/power steering delete
alum light weight crank pulley
corksport exhaust
i think thats it but im trying to hit big numbers but u get the idea :)
 
Last edited:
Have you dyno it?

I have a similar setting
Im running an Fp engine with;

Jspec pistons .20overbore
full work on head .80 shave
twiggys
SR camgears
626 IM
obx crankpuley
custom intake
custom exhuast
eybach valvesprings
and the best of all a 4.68 Mfactory finaldrive

I got a Megasquirt2 intaling it soon
not dyno yet

how do them twiggys work for ya?
 
Back