Engine Building - The Right Way

[Drift2XL]

From my experience, it seems that NA will beat forced induction.

My main example is a ZR-1 I built awhile back for NY. I built it out as a Muscle Inc B class missile (as much as you can). I built the engine three ways. NA, PD S/C, Cent S/C. The NA walked all over the cent S/C. The PD was closer but the NA was more managable and got better more consistant times.

The turbo does pick up the top end really well. Its the off time and feathering the gas on exit when it really loses out. The driver who gets on the gas full the fastest is usually the winner in a speced out race series. Only when huge differences in power does that go out the window.

I'm working on the "S13 Files" right now. There has been a big time drop on the one QR I have finished. Problem is I think it was line more than change in engine parts.

Needless to say a 57 on Rd Atl short is nothing to sneeze at.

[BarbecuePete]

Been a while since this threads been active but I have been building a few FWD cars in B-class recently and wanted to ask peoples thoughts on a few of the things I've noticed with engine building... Im building full lightweight cars so im limited in how many power parts I can add...

I always start by adding the race fuel and ignition upgrdes, my thoughts behind this are that these 2 parts (engine mangement / igintion) although they don't give much by themselves are vital to getting the most from any other upgrades..

I've notcied that torque doesn't have an effect on PI, so for example you can build a 250hp engine with 240 lb-ft or 210lb-ft of torque for the same PI.. For these types of cars I would assume that more torque is going to mean a faster car, as it will accelerate faster and pull better out of corners..

Also when adding parts to the engine does adding say all first level upgrades or one big race level upgrade say race turbo or cams (assuming they gave the same overall hp & tq) affect the way engine actually performs on the track In terms of engine response / acceleration?

I have noticed that if I can fit the second level and above of engine block upgrade with say first stage  exhaust / intake the engine feels like it responds a lot better than if I was to add race exhaust / Intake upgardes and stay with standard block or even first level of upgrade...

Oh and just one more thing... lol

With turbocharged engines is it better to have a slightly lower peak torque figure but produced higher up in the rev range, than lots of torque low down in the rev range that trails off at high revs... This is an example of the VW beetle, the figures are very rough..

Both engines produce the same peak HP

Std Turbo - 270 lb-ft @ 3000 rpm / 160 Hp @ 7200

1st stage turbo - 250 lb-ft @ 5200 / 180 Hp @ 7200

Dodgy diagram... lol
Red line is torque, First graph is with the std turbo, second is with first stage turbo..




EDIT:- Lots of questions I know, just brainstorming really, I wouldn't try and answer them all in one go... 

Edit: I just fixed the Hp ref in Turbo listings above (they were ft-lb) for clarity's sake.  Good post BBQ.  $

[Drift2XL]

Whoo!   That's quite a list.

I...got to do some research.

I would say that with at least aero invovled, torque is the way to go.....until you can't control it (B Class MInc.?) I have built a couple of cars during a challenge at Suzuka west. with virtually the same stats. An S2000 and a Solstice, both with interchangable stats.  The top speed of the Honda was around 4.7 and accel was at 4.3. The Solstice turned it around with a 4.7 accel and only topping out with a 4.3.

The handling ratings were about even. The Solstice was a full second faster than the Honda. I even tried to go with a six speed trans with the Honda, but that didn't even even it up. So the accel is really the best way to lower lap times, as you guessed.

Turbo.... I will have to get back to you later. I got someone tapping a foot with a purse in their hands right now. I'll get back to you later tonight if I can get back to the computer at a decent hour.

[Drift2XL]

I've been testing a few theories of my own tonight. The first one is something I noticed awhile back. That a turbo car spools faster with an upgraded intercooler.

I finally got my proof. I went out with the Beetle. I went to the telemetry on the replay and counted frames from start of the 3-4 shift to the return to full boost.

Stock turbo              Sport turbo           
no IC  - 51 fr            no IC  - 88 fr
sp IC  - 48 fr            sp IC  - 80 fr
rc IC  - 48 fr             rc IC  - 73 fr

So an upgraded IC wil get you back to full boost faster.

I also noticed that the stock torque peak was at 3000-3500 RPM. Man that's low. Good for milage, not too good for performance. I built it as a standard torque build, I believe that it had a tq peak of 235 or close to it. When the shift was completed and boost returned to full it just tickled 220ft/lbs and tailed off from there. I was shifting at the 6500 redline. Not near the fuel cutoff. With the low end on the 1.8t, it might actually like to be short shifted a bit.

The fastest accelerating car will be the one with the most average HP and tq through the intended RPM range.
Probably why the big block muscle cars seem to like at least one head/cam package. To move the torque peak up nearer to the HP peak. Just on the stats it would seem that the turbo upgrade would work better.

I did build a balanced engine packege, but I forgot to document it. I do know that on a ten roll, from the red line at the beginning of the Motegi west frontstretch to the S/F line it hit 106. Just the same as a stock turbo torque build that's in it right now.

The detraction from the turbo upgrade may be the increase in spool up time. While it is boosting over twice the pressure of the stock, its taking almost twice as long to get it up to full boost too. Also, its not hitting full boost until over 5000, where the stock was full on at 4000. It seems that it might like to open up the gearing on it with the turbo upgrade. The Beetle seemed to just hit full boost and then it was time to shift again. But then I did build a five speed for it also.

[Blooze]

What a great (and definitive) post, Drift!  Good job!

I am particularly impressed at the idea of using the Frame Rate as a unit of time.  That hadn't occurred to me.  In thinking about it, however, it does raise a question.  Is the Frame Rate a constant?  I don't know.  I do know that in the Windows OS, areas of the screen that have not changed are not redrawn.  I wonder if a similar algorythm is applied to the refresh rate.

@BBQ - I was unable to reproduce your numbers on the Beetle Engine, specifically, the condition where the Sport Turbo upgrade produced less torque than the Standard package.  Could you outline the builds that produced these numbers?

Re: Engine Upgrade Path - a few thoughts...

One of the things I use when building out an engine is the Torque/Hp ratio.  I have no real data to explain why, other than the idea that the closer the ratio is to 1, the better.  Working off this makes me make this decision: if (Tq/Hp < 1, buy Torque, buy Cam)

For this reason, I have a bit of a worksheet for doing the arithmetic on engine parts.  Below is a table of how the Beetle fares with the various race level parts.

Race Part	Hp	Tq	Tq/Hp
Stock	177	169	0.955
Intake	200	193	0.965
Exhaust	201	195	0.970
Iginition	196	189	0.964
Fuel	197	190	0.964
Cam	238	195	0.819
Engine	205	199	0.971
Turbo	216	189	0.875
Intercooler	186	179	0.962

Applying my logic, the upgrade path would be Engine first, then Exhaust, Intake, etc...  Interestingly, the Cam upgrade reduces the Peak Torque value by 500 RPM.  It is this reason that you will find me using the 90% Hp to define my operating range.

Is one flavor of Hp upgrade better than another?  I think not.  Well, it is, but that is handled by the torque value of the various parts.  I don't think there is another set of hidden variables used to calculate power and the like.  Consider that the Hp and Torque must be constantly calculated based on RPM (throttle input) by the physics engine (for eight cars), and one would have a reason for keeping these calcs as simple as possible.

Sorry for carrying on so... 

Great discussion guys!

$

[BarbecuePete]

@BBQ - I was unable to reproduce your numbers on the Beetle Engine, specifically, the condition where the Sport Turbo upgrade produced less torque than the Standard package.  Could you outline the builds that produced these numbers?

The engine builds are pretty similar Blooze...

Sport Turbo	Standard Turbo
Race Fuel	Race Fuel
Race Ignition	Race Ignition
Sport Intercooler	Sport Intercooler
Std Exhaust	Race Exhaust
243 bhp @ 6000 rpm	244 bhp @ 6000 rpm
231 lb-ft @ 4100 rpm	238 lb-ft @ 2800 rpm

I went and did a bit of investigation myself with a quick dyno run of both engine builds and it seems I may have been slightly wrong on the amount of drop off in torque given by the standard turbo, I think I was mislead by the changes in the power graph that appears on the left hand side when changing engine parts, Here's the dyno graph with the 2 builds on...



Also the benchmark figures turn out like this...

	Sport Turbo	Std Turbo
0-60	5.555	5.517
0-100	11.940	11.818
Top Speed	137.3	137.6

So it would seem that I would actually be better going back to the stanadrd turbo... the extra drop off I was seeing when building the engine was more a result of an optical illusion as the torque from the sport turbo still drops off as much but because its flatter it doesn't look like it does... In reality it never produces more torque than the standard turdo at any given revs... However is its also worth considering the extra 13 lbs of wheel weight involved in this change when looking at the whole car as a package or do the raw figures win out...

Its also put another thought in my head though... Turbocharged engines... Concetrate on intercooler / exhaust / intake?      Faster spooling / better breathing

[BarbecuePete]

More thoughts on engine building after playing with a 2000GT in C-class...

My original engine build went for :-

Race Fuel
Race Exhaust
190hp and 165lb-ft of torque. (I think, not in front of the 360 right now)

After a few test runs I decided to see if building the engine a different way would net me maybe an extra hp or lb-ft of torque without bumping the PI up (or maybe 1-2 pi)

After trying a few different parts I ended up with:

Street Intake
Sport Exhaust
Street Sport Ignition
Street Fuel
Street Block

190hp and 165lb-ft of torque. same as before so back to 550Pi.

Now looking at the raw figures here there should be no difference between how the two cars perform but when driving the second build felt a bit stronger in the mid range than the original build and didn't seem to die off at high revs. (Not by much but was maybe worth an extra 1 or 2 mph at the top of the hill on MV)

So I think it adds weight to my theory that upgrading every (most) part(s) of the engine slightly rather than one large upgrade gives a better stronger engine for the same hp and Pi. Similar to RL in that putting a full race exhaust on a FWD econo box won't give the same performance (even if you get the same HP) as upgrading the fuel / ignition / block and putting a mildly upgraded exhaust on.

So has anyone else found this when building up cars? Anyone got any thoughts or am I just imagining it?


Edit: corrected Ignition to Sports level upgrade.

[sk15kev]

In theory that should be the case, as each part is linked somehow and the engine should only be as strong as its weakest part. (bit of motivational speak for you).

Whether the game sees I tlike that I am not sure, be interesting to see the results in an engine that is torque heavy prior to upgrades.

[fndrbndr]

Pete, have you looked at the dynos for the two cars, or tried making your own?  That should give you an answer, though I'd imagine that you're onto something.  I always go with race exhaust and intake first, but maybe the ricers on campus are starting to rub off on me. lol

[bimmerlovere39]

I might look through the GT400 replays to try and get some dynos... might be interesting to see comparative HP & torque curves.

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