Project 2.

[Brett027]

In practice a small increase from 2 inch to 2.25 inch, but that small diameter change increases the flow (in theory) by about 26%. Combined with the better design of the pipe layout (particularly between the extractors and the muffler) and importantly, the uniform pipe size through the bends, the overall change makes a substantial difference. Where the bends were before cut the diameter and therefore the flow considerably. The difference is noticeable.

[Brett027]

I put an order in with Rares on line on the weekend. They are usually quick to post and bits arrive in a few days. I sent an email to see how it was going and this is the reply:

"Thanks for reaching out.

I can confirm we have stock of your order and it will be sent out at our earliest convenience"

I'm thinking that customer service attitudes are not quite what they used to be

[EK283]

I deal with the public in my present role and I can tell you it's not just customer service that is going down hill.

It really shocks me that this modern world is full of selfish victims.

People dont wave if you let them in the traffic, they wont say please or thank you, and will give you an entitled gobfull at a drop of a hat.

I say relax the rules and let people give each other a fist overhaul when required !

Getting older worries me sometimes as a lot of the young punks have no morals.

Why is this happening ?

Greg

[Blacky]

I deal with the public in my present role and I can tell you it's not just customer service that is going down hill.

It really shocks me that this modern world is full of selfish victims.



Getting older worries me sometimes as a lot of the young punks have no morals.

Why is this happening ?

Greg

It has happened because of the "everyone gets a trophy" and the "smacking is child abuse" mentality - younguns aren't learning that there are consequences for bad behaviour nor are they learning about only the top of the heap get the chocolate - therefore entitled little shits who have no respect for others are in abundant supply.

[Errol62]

2.25sq/2sq=1.26 so yes. Simple geometry.


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[Harv]

It's a bit trickier than that. If the flow is turbulent (likely in an exhaust), then you don't square the numbers (2.25²/2² = 25%). The answer is somewhere between (2.25^2.5/2^2.5 = 34%) and (2.25^2.7/2^2.7 = 37%). If the exhaust is long, the flow low and the bore large, the flow becomes more laminar and you get (2.25⁴/2⁴ = 60%).

As the gases change flow rate, they also change the amount of heat they lose in the exhaust pipe. This changes viscosity and density of the gas, which also changes the flow. Those calculations get harder.

Seems a bit fancy, but when you see the amount of money a NASCAR or Top Fuel team will put in to get a few % increase in flow then it makes more sense.

Cheers,
Harv

[Brett027]

Wow, thanks Harv. The exhaust fellow said that with better flow the muffler and pipe is less hot so that all makes sense too. I can attest that better flow means more ponies

[Errol62]

Yes alright Harv. My rationale is inclined to be static…


FB ute fixer upper, EK van on rotisserie

[funkyscooter]

I put an order in with Rares on line on the weekend. They are usually quick to post and bits arrive in a few days. I sent an email to see how it was going and this is the reply:

"Thanks for reaching out.

I can confirm we have stock of your order and it will be sent out at our earliest convenience"

I'm thinking that customer service attitudes are not quite what they used to be

Last 'Rares' purchase I made for the 1/4 vent rubbers was through SpeedSpares - has Rares branding on the site. Paid an extra couple of dollars to have it mailed express post. Was fitting the rubbers to the car the next day.
No excuse - but that reply smacks of AI.

[Brett027]

Yes Lawrence is amazing at Speeds. I think he is no longer a Rares franchise unfortunately.

[EK283]

Wow, thanks Harv. The exhaust fellow said that with better flow the muffler and pipe is less hot so that all makes sense too. I can attest that better flow means more ponies

Better flow absolutely can make more power, but the dyno tells the real story. On a chassis or engine dyno, you typically see horsepower increase when exhaust restriction is reduced because the engine spends less work pushing exhaust gases out (reduced pumping losses). The gains depend on how restrictive the original system was.

The important point is that bigger flow doesn't always equal more power. Dyno testing regularly shows that an exhaust that's too large can reduce exhaust gas velocity and scavenging, costing torque in the low and mid-range. That's why a properly sized system often outperforms the biggest one.

As for heat, the exhaust can actually feel cooler downstream because the gases are moving through the system faster and spending less time transferring heat into the pipes and mufflers. However, exhaust gas temperature at the engine itself doesn't necessarily decrease just because the exhaust flows better.

The dyno is the only way to measure and it's common to see a well-designed exhaust pick up anywhere from 5–20 hp on a naturally aspirated V8 depending on the engine combination, while poorly matched systems can lose power despite flowing more air.

Just saying.

Greg

[Brett027]

Thanks Greg.
I understand that 2.25 inch diameter is the sweet spot for holden sixes, and matches to the extractor outlet size. My dyno is my butt, and my butt says its degrees quicker than it was driving it in for the work compared to driving it home.

[EK283]

Thanks Greg.
I understand that 2.25 inch diameter is the sweet spot for holden sixes, and matches to the extractor outlet size. My dyno is my butt, and my butt says its degrees quicker than it was driving it in for the work compared to driving it home.

Ha Ha, ultimately thats all that matters !!!

Greg

[Errol62]

When I got the exhaust made on the ute the guy said he wasn’t sure that 2” would not be too big for it. He was not dvperienced on older cars so he sought some advice that confirmed it would be okay. Since we got hold of the sedan from Trev, I am sold on the 2.25” system. It sounds so much better for a start. Okay, it is a 202 vs 186, and it has a hot dog resonator in addition to sports muffler. I would definitely go the 2.25” next time, even if just for the sound. Oh, and my seat of the pants-o meter tells me the car goes better when ever I do any work to or spend money on mechanicals.


FB ute fixer upper, EK van on rotisserie

[Brett027]

A bit of work to get the ute's front suspension back to spec.

The drivers side top wishbone was 10mm offset to the firewall, and the lower wishbone 13 mm offset to the front. They are meant to be equal each side. The reason I went looking was there was an increasing squeak on that side of the car and when I went to grease everything, the top wishbone front grease nipple would not take any grease. Some rudimentary investigation found that the pin was hard up against the bush and there was no way grease could get past and these two bits were rubbing against each other- hence the squeak.

This is not a job I was happy about, having paid someone to put the new bushes and ball joints in about 12 months ago. Anyway, took my time and now they are done.

I had a spring compressor made from a threaded rod, but in the end just used a trolley jack to compress the bottom wishbone against the car's weight after putting the front on stands. My springs are 3inch shorter than standard (9inches compared to 12.5inches standard) and because the length is shorter, this makes the jack method much simpler and a little less risky. I unbolted the steering arm and brake caliper, removed the shock absorber and sway bar and moved them out of the way and tied up the caliper. Didn't disconnect the steering arm ball joint, or the brake lines, so an easy reassembly.

To remove the lower front ball joint I supported the lower wishbone with the trolley jack, reversed the castelated nut and released it a few turns, supported the hub with another jack so some weight was on the axle and gave it a couple of solid taps. The spring force encourages the ball joint to release easily this way. Once the lower ball joint is removed, gently lowered the wishbone until the pressure is off the spring. It only takes a few minutes, but you need to be carefull. I had my spring compressor rod sitting in the top shock absorber hole, just in case the jack slipped to stop the spring flying out towards me.

My biggest fear in this job was that the wishbone bush holes would be worn out, but luckily they were fine and after a few goes removing and screwing back in, I was able to get the even spacing required and retorque the bushes to 60ft/lbs.

For Stephen, who asked some time ago, the front springs are 16.5mm thick wire and 9 inches high when free. There is a 15mm cushion on top.