VQ 304 - Cheap Street Fasts

[[tuffvq]]

HI All,

First post here - thought I might try and keep some sort of record of playing around with how this car runs.

I've just bought an NVRAM and USB comms package and hooked it up to my 808. After a crash course in ADX/XDF/BIN files and getting XP to work, I have an ECU that literally fired up the car first shot. I was impressed. Car combo is as follows:

Engine: Stock 304 Bottom end (rings and bearings replaced, stock 8.4:1 comp), Mild hand-port heads, 2.02″ inlet valves, standard exhaust valves (both Stainless), Crane 218@.050, 110LSA cam, speed pro lifters, speed pro chrome moly pushrods, YT 1.65:1 Roller Rockers, LT1 Valvesprings, Rollmaster double row chain, Deburred block and smoothed valley, Powerbond Street Balancer, High Energy Super Pan sump.

172rwkw, 12.6@108mph, 1.80 60ft, 225 Bridgestones, 3.89 gears.

Fuel System: Group A 24lb Injectors, standard rail, Turbosmart fuel reg, Bosch 044 pump from 1.5L surge tank, Peirburg E85 Low pressure in-tank pump.

Exhaust: 1 5/8″ Tri-Y Extractors, twin 2.5″ into twin 3″ metal cats, twin 2.25″ mufflers into single 3″.

Transmission: Pro Convertors 9″ 4000rpm stall, Fully rebuilt TH700 auto with: wider Hi-energy Kevlar 204 band, Hi-energy 3/4 frictions, Hi-energy forward frictions, ‘The Beast’ reaction shell, Steel thrust below shell, Sonnax bush kit, Transgo Stage 2 Shift Kit, Billet 2nd and 4th gear servos, 0.500″ Bosst valve, larger 1-2 accumulator, B&M Pro Ratchet, B&M Monster Trans cooler with Thermostat controlled SPAL fan and -6 braided feed lines, TCI Super Pan.

Differential: BW78 IRS, 4.11 gears, Torquelock centre.

Brakes: VS Booster, VT Master Cylinder with RBS Adaptor plate, PBR Performance front calipers, slotted rotors, billet adaptor hubs, braided lines. Slotted rear rotors, bendix advance pads and B&M line lock.

Suspension: Kings VS V6 Ultralows front, SSSL springs rear, Monroe GT shortened shocks front and rear, Nolathane adjustable strut tops, Noltec 2 point inner camber kit, Nolathane non-adjustable outer bushes, Noltec rear k-frame bushes, VS trailing arms, strengthened and modified VP K-frame (additional inner arm mounting points to correct camber), Custom diff mount (Nolathane bushes), Nolathane radius rod bushes (k-frame and control arm), Nolathane control arm bushes, Nolathane sway bar mounting bushes and heavy duty link pins.

Wheels: 19×8″ VY GTS in Shadow Chrome

Interior: Standard with Autometer transmission temperature, voltmeter, mechanical oil pressure and mechanical water temperature guages, Innovate LC-1 Wideband, Integrated shift light and autometer oil pressure warning lights.

Other: Crane Hi-6 Ignition system, smoothed engine bay, VQ Caprice fog lights.

[[tuffvq]]

So now we get to the stuff you guys are probably more interested in.
Took the car for its first drive last night with the NVRAM installed. I have an Innovate LC-1 Wideband which I am yet to connect to the ECU (Pin D9?), I'll have to do this sooner rather than later.

The intake manifold on this car is a VN Group A replica I built about 8 or 9 years ago as my first aluminium project (It doesn't look great - if I built it again it would look much better!). It runs the same plenum volume as the factory unit with 2 inch longer runners at 44mm dia. (10" total bellmouth to valve head).




First thing first, it seems as though the way my intake manifold works needs to be looked at. It runs twin 60mm V6 throttles which open simultaneously. The IAC port on the secondary throttle is welded closed, however it seems as though there is still too much airflow getting into the engine as I have ~50KPa at idle. From what I understand I should be aiming for 25-30kPa? I'll have to look at if there is a vacuum leak also (i suspect there might) as the manifold was not machined after all of the welding.

As such, the car is typically idles around 900-1000rpm with the occasional flutuation. I want it to be lower than this. I also have the IAC sitting on 3 steps at this time, which suggests to me the IAC is fully closed and is still not able to meet the target idle speed (at 750rpm for now).

The next issue is TPS. With the throttle fully closed it sits on 0% readout (I expected it would have been a couple of %?), and since the throttles actuate simultaneously, it requires stuff all throttle input to move along (2-3%). This hasn't been an issue for me driving it as i'm used to it, and also the convertor takes up some of the slack, but I would like to change this for both driveability and the fact that (as I understand it) it would mean I'm doing a bit of cruising on the idle table. When rolling into the throttle, I can obtain 90-100kPa with as little as 35-40% TPS. This would also be to do with the actuation of the throttles, as well as the flow of the top end of the engine (heads and intake). This manifold was designed to be run on a much stronger engine, I just never got around to building something better.

I've noticed also that I can make wholesale changes on the 20-100kPa VE table and unless I'm getting up it, it makes no difference as far as I cna tell to the mixtures. I think this is to do with the above.

So in summary, I'm guessing my best approach would be to look at the throttles, check for vac leaks, hookup the wideband and start logging. Oh, and get more familiar with the tables!

[pman92]

Check for vac leaks. If good wind the throttle stop screws out to bring the IAC steps up to around 20.

As for the small amount of throttle pedal travel for big power increase, it may be possible to make a linkage setup that progressively opens the throttles. So first 10% of pedal travel only opens the throttles 3%, but last 10% of pedal travel opens throttles last 20%. If you know what I mean.
Ecotech throttle body's are not straight bore in the middle. They have lips to create a similar effect. Have a look at one and you will see what I mean.

As for MAP readings. You will probably get 100kPa at 5% or 10% TPS at 800rpm. But 10kPa at 10% TPS at 5000rpm. If it's at 100KPA it means it's at full load. The throttle is open further than the engine is currently spinning kinda. It's making power. I'm not very good at explaining it.
As long as you maintain 90 to 100 kPa at full throttle right up until redline it means your intake, air filter, throttles etc are not restricting and limiting the power the engine can make.

[vlad01]

TPS should be 0% when the throttle is closed. % TPS refers to how much throttle you are pressing and doesn't include idle stop adjustments. The ECU zeros out the reading of the TPS when powered up within a given range of it being open, its outside of that range it will throw an error.

Also as for the idle Kpa, that doesn't sound that bad at all but can be better when tuning the fuelling and ignition to optimum values, it will bring the Kpa down. MBT always has the best vacuum and so does the correct AFR.

[[tuffvq]]

Thanks for the feedback guys.

This is definitely a steep learning curve!

[[tuffvq]]

Also I was thoroughly surprised at how well it run off (what I understand to be) a factory BLCF VP V8 tune. All i changed was the KINJFLOW value and boom, fired right up.

[vlad01]

yeah looking at the engine specs its very tame so yeah it should run easy of a stock tune but I can tell you there will be a lot more out of it now with that manifold and a proper tune.

[[tuffvq]]

I should clarify.

I've had it running off a 'mail order' delco chip for something like 7 years, whilst idling a little rich and probably a bit conservative on the timing. It went quite well (12.6 qtr) but I want to be able to learn to tune on what is effectively my nugget motor before I go chasing more power.

[vlad01]

it should definitely get some good gains then, mail order tunes are not the greatest unless its been perfected by means of a dyno on the exact same combo.

12.6 1/4 is mighty impressive for the little power output it has.

[immortality]

it should definitely get some good gains then, mail order tunes are not the greatest unless its been perfected by means of a dyno on the exact same combo.

12.6 1/4 is mighty impressive for the little power output it has.

Or a very good driveline make very good use of said power......

But I agree, it's is a very good effort.